DTC P0480, P0481, P0691, P0692, P0693, or P0694. Buick Regal 2009

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2009 🢒 Regal 🢒 DTC 🢒 DTC P0480, P0481, P0691, P0692, P0693, or P0694

DTC P0480, P0481, P0691, P0692, P0693, or P0694 LTD and LE5

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit

DTC P0481: Cooling Fan Relay 2 Control Circuit

Diagnostic Fault Information

KR20A Cooling Fan Medium Speed 1 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480, P0481	P0480, P0481	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	P0481	P0481	P0481	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Medium speed fan inoperative without a DTC. Medium speed fan always ON without a DTC.

KR20B Cooling Fan Medium Speed 2 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480	2	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	3	2	4	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Low speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC.

KR20D Cooling Fan High Speed Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480, P0481	P0481	1	--
Relay Switch B+ Circuit	2	2	--	--
Relay Control Circuit	P0481	P0481	P0481	--
Relay Controlled Output Circuit	2	2	3	--
Medium speed fan replaced by high speed fan without a DTC. High speed fan inoperative without a DTC. High speed fan always ON without a DTC.

KR20E Cooling Fan Speed Control Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480	1	--	--
Relay Switch Ignition Circuit	P0480	1	--	--
Relay Control Circuit	2	1	3	--
Relay Controlled Output Circuit	P0480	1	4	--
High speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC. High speed fan inoperative without a DTC.

KR20F Cooling Fan Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691	P0480	--	--
Relay Switch Ignition Circuit	--	1	2	--
Relay Control Circuit	P0691	P0480	P0692	--
Relay Controlled Output Circuit	--	2	2	--
Low speed fan always ON without a DTC and, if commanded, medium speed fan replace by high speed fan without a DTC. Low speed fan and high speed fan inoperative without a DTC.

The engine control module (ECM) commands the fan ON in either high speed, medium speed, or low speed, depending on cooling requirements. In low speed, the fan is turned ON at a reduced speed. In medium speed, the fan is turned ON at a higher reduced speed. In high speed, the fan is turned ON at full speed.

In low speed operation, the ECM provides ground to ECM terminal X2 44. The KR20F Cooling Fan Relay activates and provides ground to the coils of the KR20B Cooling Fan Medium Speed 2 Relay and the KR20E Cooling Fan Speed Control Relay. The KR20E Cooling Fan Speed Control relay activates and provides power to the coil of the KR20D Cooling Fan High Speed Relay. The KR20D Cooling Fan High Speed Relay remains inactive because ECM terminal X2 15 is not grounded. The KR20B Cooling Fan Medium Speed 2 Relay provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 2 and the internal fan resistor.

In medium speed operation, the ECM provides ground to ECM terminal X2 15. The KR20D Cooling Fan High Speed Relay remains inactive because power is not provided to the coil from the KR20E Cooling Fan Speed Control Relay. The KR20A Cooling Fan Medium Speed 1 Relay activates and provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 3 and the internal fan resistor.

In high speed operation, the ECM provides ground to ECM terminals X2 15 and X2 44. As previously described, power is now provided to both cooling fan terminals 2 and 3. In addition, power and ground are now provided to the coil of the KR20D Cooling Fan High Speed Relay. The KR20D Cooling Fan High Speed Relay activates and provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 4, bypassing the resistors.

Conditions for Running the DTC

•	The ignition voltage is between 8-18V.

•	The engine speed is more than 40 RPM.

•	The ECM driver transitions from ON to OFF or from OFF to ON.

Conditions for Setting the DTC

P0480

The ECM detects an open, short to ground, or short to voltage on the low speed cooling fan relay control circuit for more than 1 second.

P0481

The ECM detects an open , short to ground, or short to voltage on the high speed cooling fan relay control circuit for more than 1 second.

Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480 and P0481 are Type B DTCs.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Command the Fan Relay 1 ON and OFF with a scan tool. The fan should turn ON at low speed and OFF with each command.

⇒	If the fan does not operate correctly, go to low speed operation malfunction.

2. Command the Fan Relay 2 and 3 ON and OFF with a scan tool. The fan should turn ON at medium speed and OFF with each command.

⇒	If the fan does not operate correctly, go to medium speed operation malfunction.

Command the Fan Relay 1, 2 and 3 ON and OFF with a scan tool. The fan should turn ON at high speed and OFF with each command.

⇒	If the fan does not operate correctly, go to high speed operation malfunction.

Circuit/System Testing

Note: Circuit/System Verification must be performed before Circuit/System Testing or misdiagnosis may result.

Low Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20E Cooling Fan Speed Control Relay

•	KR20F Cooling Fan Relay

Ignition ON, verify that a test lamp does not illuminate between relay controlled output circuit terminal of the relay connectors listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Test for less than 1.0Ω between the relay controlled output circuit terminal of the KR20F Cooling Fan Relay and ground.

⇒	If greater than the specified range, test the output circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of each relay connector listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒

If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test the relay switch controlled output circuit terminal at the KR20E Cooling Fan Speed Control Relay connector for a short to ground. If the circuit tests normal, test or replace the KR20E Cooling Fan Speed Control Relay.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay controlled output circuit terminal at the relay connectors listed below for a short to ground:

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Medium Speed 2 Relay

Install a 10A fused jumper wire between the relay coil ignition circuit terminal and the relay coil control circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector.
Verify that a test lamp illuminates between the relay switch ignition circuit terminal and the relay controlled output circuit terminal at the KR20F Cooling Fan Relay connector.

⇒	If the test lamp does not illuminate, test the relay switch ignition circuit terminal at the KR20F Cooling Fan Relay connector for an open/high resistance.

Disconnect the harness connector at the G10 Engine Cooling Fan.
Test for less than 1.0Ω between the G10 Engine Cooling Fan ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Connect the harness connector at the G10 Engine Cooling Fan.
Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector. Verify the cooling fan is activated at low speed.

⇒	If the cooling fan does not activate at low speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.

Verify that a test lamp does not illuminate between the relay coil control circuit terminal of the KR20F Cooling Fan Relay connector and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20F Cooling Fan Relay.

⇒	If not within the specified range, replace the relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20F Cooling Fan Relay connector and terminal 85 at the KR20F Cooling Fan Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20F Cooling Fan Relay connector and terminal 86 at the KR20F Cooling Fan Relay.
Command the Fan Relay 1 OFF with a scan tool. The DMM should indicate less than 1 mA

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Relay

Medium Speed Malfunction

Ignition OFF, disconnect the KR20A Cooling Fan Medium Speed 1 Relay.
Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal. Verify the cooling fan is activated at medium speed.

⇒	If the cooling fan does not activate, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Test for less than 1V between the relay coil control circuit terminal and ground.

⇒	If more than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, test the KR20E Cooling Fan Speed Control Relay for correct operation. If the relay tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20A Cooling Fan Medium Speed 1 Relay.

⇒	If not within the specified range, replace the KR20A Cooling Fan Medium Speed 1 Relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 85 at the KR20A Cooling Fan Medium Speed 1 Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 86 at the KR20A Cooling Fan Medium Speed 1 Relay.
Command the Fan Relay 1 and 2 OFF with a scan tool. The DMM should indicate less than 1 mA.

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 and 2 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test or replace the KR20A Cooling Fan Medium Speed 1 Relay.

High Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal at the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Install a 10A fused jumper wire between the relay switch ignition circuit terminal and the relay controlled output circuit terminal of the KR20E Cooling Fan Speed Control Relay connector.
Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit terminal for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒

If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20D Cooling Fan High Speed Relay connector. Verify the cooling fan is activated at high speed.

⇒	If the cooling fan does not activate at high speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Ignition OFF, remove the KR20A Cooling Fan Medium Speed 1 Relay.
Test for less than 5Ω between the relay coil control circuit terminals at the relay connectors listed below:

•	KR20A Cooling Fan Medium Speed 1 Relay

•	KR20D Cooling Fan High Speed Relay

⇒	If more than the specified range, test the KR20D Cooling Fan High Speed Relay coil control circuit for and open/high resistance.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Component Testing

Ignition OFF, disconnect the applicable relay.
Test for 70-110Ω between terminals 85 and 86 of the relay.

⇒	If the resistance is not within the specified range, replace the relay.

Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the relay.

Test for less than 2Ω between terminals 30 and 87A.

⇒	If more than the specified value, replace the relay.

Install a 20A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2Ω between terminals 30 and 87.

⇒	If more than the specified value, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Relay Replacement

•	Control Module References for ECM replacement, setup, and programming

DTC P0480, P0481, P0691, P0692, P0693, or P0694 LDK with Turbocharger

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit

DTC P0481: Cooling Fan Relay 2 Control Circuit

DTC P0691: Cooling Fan Relay 1 Control Circuit Low Voltage

DTC P0692: Cooling Fan Relay 1 Control Circuit High Voltage

DTC P0693: Cooling Fan Relay 2 Control Circuit Low Voltage

DTC P0694: Cooling Fan Relay 2 Control Circuit High Voltage

Diagnostic Fault Information

KR20A Cooling Fan Medium Speed 1 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691, P0693	P0480, P0481	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	P0693	P0481	P0694	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Medium speed fan inoperative without a DTC. Medium speed fan always ON without a DTC.

KR20B Cooling Fan Medium Speed 2 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691	2	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	3	2	4	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Low speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC.

KR20D Cooling Fan High Speed Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691, P0693	P0481	1	--
Relay Switch B+ Circuit	2	2	--	--
Relay Control Circuit	P0693	P0481	P0694	--
Relay Controlled Output Circuit	2	2	3	--
Medium speed fan replaced by high speed fan without a DTC. High speed fan inoperative without a DTC. High speed fan always ON without a DTC.

KR20E Cooling Fan Speed Control Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691	1	--	--
Relay Switch Ignition Circuit	P0691	1	--	--
Relay Control Circuit	2	1	3	--
Relay Controlled Output Circuit	P0691	1	4	--
High speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC. High speed fan inoperative without a DTC.

KR20E Cooling Fan Speed Control Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691	1	--	--
Relay Switch Ignition Circuit	P0691	1	--	--
Relay Control Circuit	2	1	3	--
Relay Controlled Output Circuit	P0691	1	4	--
High speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC. High speed fan inoperative without a DTC.

Circuit/System Description

In low speed operation, the ECM provides ground to ECM terminal X2 46. The KR20F Cooling Fan Relay activates and provides ground to the coils of the KR20B Cooling Fan Medium Speed 2 Relay and the KR20E Cooling Fan Speed Control Relay. The KR20E Cooling Fan Speed Control relay activates and provides power to the coil of the KR20D Cooling Fan High Speed Relay. The KR20D Cooling Fan High Speed Relay remains inactive because ECM terminal X2 45 is not grounded. The KR20B Cooling Fan Medium Speed 2 Relay provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 2 and the internal fan resistor.

In medium speed operation, the ECM provides ground to ECM terminal X2 45. The KR20D Cooling Fan High Speed Relay remains inactive because power is not provided to the coil from the KR20E Cooling Fan Speed Control Relay. The KR20A Cooling Fan Medium Speed 1 Relay activates and provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 3 and the internal fan resistor.

In high speed operation, the ECM provides ground to ECM terminals X2 45 and X2 46. As previously described, power is now provided to both cooling fan terminals 2 and 3. In addition, power and ground are now provided to the coil of the KR20D Cooling Fan High Speed Relay. The KR20D Cooling Fan High Speed Relay activates and provides power to the G10 Engine Cooling Fan motor through cooling fan terminal 4, bypassing the resistors.

Conditions for Running the DTC

•	The ignition voltage is between 8-18V.

•	The engine speed is more than 40 RPM.

•	The ECM driver transitions from ON to OFF or from OFF to ON.

Conditions for Setting the DTC

P0480

The ECM detects an open on the low speed cooling fan relay control circuit for more than 1 second.

P0481

The ECM detects an open circuit on the high speed cooling fan relay control circuit for more than 1 second.

P0691

The ECM detects a short to ground on the low speed cooling fan relay control circuit for more than 1 second.

P0692

The ECM detects a short to voltage on the low speed cooling fan relay control circuit for more than 1 second.

P0693

The ECM detects a short to ground on the high speed cooling fan relay control circuit for more than 1 second.

P0694

The ECM detects a short to voltage on the high speed cooling fan relay control circuit for more than 1 second.

Action Taken When the DTC Sets

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Command the Fan Relay 1 ON and OFF with a scan tool. The fan should turn ON at low speed and OFF with each command.

⇒	If the fan does not operate correctly, go to low speed operation malfunction.

2. Command the Fan Relay 2 and 3 ON and OFF with a scan tool. The fan should turn ON at medium speed and OFF with each command.

⇒	If the fan does not operate correctly, go to medium speed operation malfunction.

Command the Fan Relay 1, 2 and 3 ON and OFF with a scan tool. The fan should turn ON at high speed and OFF with each command.

⇒	If the fan does not operate correctly, go to high speed operation malfunction.

Circuit/System Testing

Note: Circuit/System Verification must be performed before Circuit/System Testing or misdiagnosis may result.

Low Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20E Cooling Fan Speed Control Relay

•	KR20F Cooling Fan Relay

Ignition ON, verify that a test lamp does not illuminate between relay controlled output circuit terminal of the relay connectors listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Test for less than 1.0Ω between the relay controlled output circuit terminal of the KR20F Cooling Fan Relay and ground.

⇒	If greater than the specified range, test the output circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of each relay connector listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay controlled output circuit terminal at the relay connectors listed below for a short to ground:

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Medium Speed 2 Relay

Install a 10A fused jumper wire between the relay coil ignition circuit terminal and the relay coil control circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector.
Verify that a test lamp illuminates between the relay switch ignition circuit terminal and the relay controlled output circuit terminal at the KR20F Cooling Fan Relay connector.

⇒	If the test lamp does not illuminate, test the relay switch ignition circuit terminal at the KR20F Cooling Fan Relay connector for an open/high resistance.

Disconnect the harness connector at the G10 Engine Cooling Fan.
Test for less than 1.0Ω between the G10 Engine Cooling Fan ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Connect the harness connector at the G10 Engine Cooling Fan.
Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector. Verify the cooling fan is activated at low speed.

⇒	If the cooling fan does not activate at low speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.

Verify that a test lamp does not illuminate between the relay coil control circuit terminal of the KR20F Cooling Fan Relay connector and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20F Cooling Fan Relay.

⇒	If not within the specified range, replace the relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20F Cooling Fan Relay connector and terminal 85 at the KR20F Cooling Fan Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20F Cooling Fan Relay connector and terminal 86 at the KR20F Cooling Fan Relay.
Command the Fan Relay 1 OFF with a scan tool. The DMM should indicate less than 1 mA

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Relay

Medium Speed Malfunction

Ignition OFF, disconnect the KR20A Cooling Fan Medium Speed 1 Relay.
Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal. Verify the cooling fan is activated at medium speed.

⇒	If the cooling fan does not activate, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Test for less than 1V between the relay coil control circuit terminal and ground.

⇒	If more than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, test the KR20E Cooling Fan Speed Control Relay for correct operation. If the relay tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20A Cooling Fan Medium Speed 1 Relay.

⇒	If not within the specified range, replace the KR20A Cooling Fan Medium Speed 1 Relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 85 at the KR20A Cooling Fan Medium Speed 1 Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 86 at the KR20A Cooling Fan Medium Speed 1 Relay.
Command the Fan Relay 1 and 2 OFF with a scan tool. The DMM should indicate less than 1 mA.

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 and 2 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test or replace the KR20A Cooling Fan Medium Speed 1 Relay.

High Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal at the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Install a 10A fused jumper wire between the relay switch ignition circuit terminal and the relay controlled output circuit terminal of the KR20E Cooling Fan Speed Control Relay connector.
Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit terminal for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20D Cooling Fan High Speed Relay connector. Verify the cooling fan is activated at high speed.

⇒	If the cooling fan does not activate at high speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Ignition OFF, remove the KR20A Cooling Fan Medium Speed 1 Relay.
Test for less than 5Ω between the relay coil control circuit terminals at the relay connectors listed below:

•	KR20A Cooling Fan Medium Speed 1 Relay

•	KR20D Cooling Fan High Speed Relay

⇒	If more than the specified range, test the KR20D Cooling Fan High Speed Relay coil control circuit for and open/high resistance.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Component Testing

Ignition OFF, disconnect the applicable relay.
Test for 70-110Ω between terminals 85 and 86 of the relay.

⇒	If the resistance is not within the specified range, replace the relay.

Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the relay.

Test for less than 2Ω between terminals 30 and 87A.

⇒	If more than the specified value, replace the relay.

Install a 20A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2Ω between terminals 30 and 87.

⇒	If more than the specified value, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Relay Replacement

•	Control Module References for ECM replacement, setup, and programming

DTC P0480, P0481, P0691, P0692, P0693, or P0694 LDK with Dual Fan

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691, P0693	P0480, P0481	--	--
Relay Switch Ignition Circuit	1	1	--	--
Fan 1 Relay Control Circuit	P0691	P0480	P0692	--
Fan 2 Relay Control Circuit	P0693	P0481	P0694	--
Relay Controlled Output Circuit	1	1	2	--
Fans inoperative without a DTC. Fans always ON without a DTC.

Circuit/System Description

The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.

Low Speed

In low speed operation, the ECM applies ground to the coil side of the following relays with the cooling fan relay 1 control circuit:

•	Cooling Fan Left Low Speed Relay

•	Cooling Fan Right Low Speed Relay

•	Cooling Fan Speed Control Relay

This energizes the relay coils. The low speed cooling fan relays supply power to the appropriate cooling fan motor through an internal fan resistor. The fan speed control relay contacts close and supply a direct ground path for the left cooling fan motor. The right cooling fan motor is connected to a dedicated ground. This results in both fans operating at low speed.

Medium Speed

In medium speed operation, the ECM commands the low speed fan relays, and the speed control relay off. The ECM simultaneously commands both of the cooling fan high speed relays on with the cooling fan relay 2 control circuit. The cooling fan motors are supplied power directly from the cooling fan high speed relays. The right cooling fan is connected to a dedicated ground, and operates at high speed. The left cooling fan is supplied a ground through the right cooling fan resistor and fan motor, which is connected to the de-energized cooling fan speed control relay. This results in the left cooling fan operating at a reduced speed.

High Speed

In high speed operation, the ECM applies a ground to the coil side of all five cooling fan relays. When energized, the high speed relays apply voltage directly to the cooling fans through the switch side of the relays. The energized cooling fan speed control relay provides a direct ground circuit for the left cooling fan. This arrangement allows each fan to receive full voltage and operate at high speed.

Conditions for Running the DTC

•	The ignition voltage is between 8-18V.

•	The engine speed is more than 40 RPM.

•	The ECM driver transitions from ON to OFF or from OFF to ON.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 1 second.

Action Taken When the DTC Sets

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate fan relays ON and OFF with a scan tool. You should hear the relays click when commanded ON and OFF.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Ignition OFF, disconnect the appropriate cooling fan relays.
Ignition ON, verify that a test lamp illuminates between each relay coil ignition voltage circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.

Test for 70-100 Ω between terminals 85 and 86 of each relay.

⇒	If not within the specified range, replace the relay.

Note: Perform the remainder of this procedure for each of the appropriate relays.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the relay connector and terminal 85 at the relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the relay connector and terminal 86 at the relay.
Command the relay OFF with a scan tool. The DMM should indicate less than 1 mA.

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the relay ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, the relays for correct operation and replace the faulty relay.

Component Testing

Ignition OFF, disconnect the cooling fan relay.
Test for 70-110 Ω between terminals 4 and 6.

⇒	If the not within the specified range, replace the relay.

Test for infinite resistance between the following terminals:

•

2 and 6

•

2 and 8

•

2 and 4

•

4 and 8

⇒	If not the specified range, replace the relay.

Install a 20 A fused jumper wire between relay terminal 4 and B+. Install a jumper wire between relay terminal 6 and ground. Test for less than 2 Ω between terminals 2 and 8.

⇒	If greater than the specified range, replace the relay.

Note: This step is only for the KR20E cooling fan speed control relay.

Remove the jumper wires. Test for less than 2 Ω between terminals 2 and 5.

⇒	If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Relay Replacement

•	Control Module References for ECM replacement, setup, and programming

DTC P0480, P0481, P0691, P0692, P0693, or P0694 LDK with Single Fan

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit

DTC P0481: Cooling Fan Relay 2 Control Circuit

Diagnostic Fault Information

KR20A Cooling Fan Medium Speed 1 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480, P0481	P0480, P0481	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	P0481	P0481	P0481	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Medium speed fan inoperative without a DTC. Medium speed fan always ON without a DTC.

KR20B Cooling Fan Medium Speed 2 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480	2	--	--
Relay Switch B+ Circuit	1	2	--	--
Relay Control Circuit	3	2	4	--
Relay Controlled Output Circuit	1	2	3	--
Low and medium speed fan inoperative without a DTC. Low speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC.

KR20D Cooling Fan High Speed Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480, P0481	P0481	1	--
Relay Switch B+ Circuit	2	2	--	--
Relay Control Circuit	P0481	P0481	P0481	--
Relay Controlled Output Circuit	2	2	3	--
Medium speed fan replaced by high speed fan without a DTC. High speed fan inoperative without a DTC. High speed fan always ON without a DTC.

KR20E Cooling Fan Speed Control Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0480	1	--	--
Relay Switch Ignition Circuit	P0480	1	--	--
Relay Control Circuit	2	1	3	--
Relay Controlled Output Circuit	P0480	1	4	--
High speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC. High speed fan inoperative without a DTC.

KR20F Cooling Fan Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691	P0480	--	--
Relay Switch Ignition Circuit	--	1	2	--
Relay Control Circuit	P0691	P0480	P0692	--
Relay Controlled Output Circuit	--	2	2	--
Low speed fan always ON without a DTC and, if commanded, medium speed fan replace by high speed fan without a DTC. Low speed fan and high speed fan inoperative without a DTC.

Circuit/System Description

Conditions for Running the DTC

•	The ignition voltage is between 8-18V.

•	The engine speed is more than 40 RPM.

•	The ECM driver transitions from ON to OFF or from OFF to ON.

Conditions for Setting the DTC

P0480

The ECM detects an open, short to ground, or short to voltage on the low speed cooling fan relay control circuit for more than 1 second.

P0481

The ECM detects an open , short to ground, or short to voltage on the high speed cooling fan relay control circuit for more than 1 second.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Command the Fan Relay 1 ON and OFF with a scan tool. The fan should turn ON at low speed and OFF with each command.

⇒	If the fan does not operate correctly, go to low speed operation malfunction.

2. Command the Fan Relay 2 and 3 ON and OFF with a scan tool. The fan should turn ON at medium speed and OFF with each command.

⇒	If the fan does not operate correctly, go to medium speed operation malfunction.

Command the Fan Relay 1, 2 and 3 ON and OFF with a scan tool. The fan should turn ON at high speed and OFF with each command.

⇒	If the fan does not operate correctly, go to high speed operation malfunction.

Circuit/System Testing

Note: Circuit/System Verification must be performed before Circuit/System Testing or misdiagnosis may result.

Low Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20E Cooling Fan Speed Control Relay

•	KR20F Cooling Fan Relay

Ignition ON, verify that a test lamp does not illuminate between relay controlled output circuit terminal of the relay connectors listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Test for less than 1.0Ω between the relay controlled output circuit terminal of the KR20F Cooling Fan Relay and ground.

⇒	If greater than the specified range, test the output circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of each relay connector listed below and ground:

•	KR20B Cooling Fan Medium Speed 2 Relay

•	KR20F Cooling Fan Relay

⇒

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay controlled output circuit terminal at the relay connectors listed below for a short to ground:

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Medium Speed 2 Relay

Install a 10A fused jumper wire between the relay coil ignition circuit terminal and the relay coil control circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector.
Verify that a test lamp illuminates between the relay switch ignition circuit terminal and the relay controlled output circuit terminal at the KR20F Cooling Fan Relay connector.

⇒	If the test lamp does not illuminate, test the relay switch ignition circuit terminal at the KR20F Cooling Fan Relay connector for an open/high resistance.

Disconnect the harness connector at the G10 Engine Cooling Fan.
Test for less than 1.0Ω between the G10 Engine Cooling Fan ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Connect the harness connector at the G10 Engine Cooling Fan.
Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20B Cooling Fan Medium Speed 2 Relay connector. Verify the cooling fan is activated at low speed.

⇒	If the cooling fan does not activate at low speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.

Verify that a test lamp does not illuminate between the relay coil control circuit terminal of the KR20F Cooling Fan Relay connector and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20F Cooling Fan Relay.

⇒	If not within the specified range, replace the relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20F Cooling Fan Relay connector and terminal 85 at the KR20F Cooling Fan Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20F Cooling Fan Relay connector and terminal 86 at the KR20F Cooling Fan Relay.
Command the Fan Relay 1 OFF with a scan tool. The DMM should indicate less than 1 mA

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20B Cooling Fan Medium Speed 1 Relay

•	KR20F Cooling Fan Relay

Medium Speed Malfunction

Ignition OFF, disconnect the KR20A Cooling Fan Medium Speed 1 Relay.
Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal. Verify the cooling fan is activated at medium speed.

⇒	If the cooling fan does not activate, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Test for less than 1V between the relay coil control circuit terminal and ground.

⇒	If more than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, test the KR20E Cooling Fan Speed Control Relay for correct operation. If the relay tests normal, replace the K20 ECM.

Test for 70-110Ω between terminals 85 and 86 of the KR20A Cooling Fan Medium Speed 1 Relay.

⇒	If not within the specified range, replace the KR20A Cooling Fan Medium Speed 1 Relay.

Ignition OFF, connect a 10A fused jumper wire between the relay coil ignition circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 85 at the KR20A Cooling Fan Medium Speed 1 Relay.
Connect a DMM set on the 10A scale between the relay coil control circuit terminal at the KR20A Cooling Fan Medium Speed 1 Relay connector and terminal 86 at the KR20A Cooling Fan Medium Speed 1 Relay.
Command the Fan Relay 1 and 2 OFF with a scan tool. The DMM should indicate less than 1 mA.

⇒	If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

Command the Fan Relay 1 and 2 ON with a scan tool. The DMM should indicate more than 100 mA.

⇒	If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

If all circuits test normal, test or replace the KR20A Cooling Fan Medium Speed 1 Relay.

High Speed Malfunction

Ignition OFF, disconnect the relays listed below:

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal at the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp illuminates, test the output circuit for a short to voltage.

Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Verify that a test lamp illuminates between the relay switch ignition circuit terminal of the KR20E Cooling Fan Speed Control Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

Install a 10A fused jumper wire between the relay switch ignition circuit terminal and the relay controlled output circuit terminal of the KR20E Cooling Fan Speed Control Relay connector.
Verify that a test lamp illuminates between the relay coil ignition circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit terminal for an open/high resistance.

Verify that a test lamp illuminates between the relay switch B+ circuit terminal of the KR20D Cooling Fan High Speed Relay connector and ground.

⇒

Connect a 60A fused jumper wire between the relay switch B+ circuit terminal and the relay controlled output circuit terminal of the KR20D Cooling Fan High Speed Relay connector. Verify the cooling fan is activated at high speed.

⇒	If the cooling fan does not activate at high speed, test the output circuit for an open/high resistance. If the circuit tests normal, test or replace the G10 Engine Cooling Fan.

Ignition OFF, remove the KR20A Cooling Fan Medium Speed 1 Relay.
Test for less than 5Ω between the relay coil control circuit terminals at the relay connectors listed below:

•	KR20A Cooling Fan Medium Speed 1 Relay

•	KR20D Cooling Fan High Speed Relay

⇒	If more than the specified range, test the KR20D Cooling Fan High Speed Relay coil control circuit for and open/high resistance.

If all circuits test normal, test the relays listed below for correct operation and replace the faulty relay.

•	KR20D Cooling Fan High Speed Relay

•	KR20E Cooling Fan Speed Control Relay

Component Testing

Ignition OFF, disconnect the applicable relay.
Test for 70-110Ω between terminals 85 and 86 of the relay.

⇒	If the resistance is not within the specified range, replace the relay.

Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the relay.

Test for less than 2Ω between terminals 30 and 87A.

⇒	If more than the specified value, replace the relay.

Install a 20A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2Ω between terminals 30 and 87.

⇒	If more than the specified value, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Relay Replacement

•	Control Module References for ECM replacement, setup, and programming