Diagnostic Instructions

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

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 and Fan S/P 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 cooling fan system consists of one electrical cooling fan, a serviceable resistor module mounted in the cooling fan shroud, and three fan relays. The relays are arranged in a series parallel (S/P) configuration that allows the engine control module (ECM) to operate the fan at low, medium, or high speeds, depending on cooling requirements. The resistor module is a self-contained unit providing a specific resistance through three individual circuits. To activate the fan, the ECM applies ground to the coil side of the applicable fan relays. The cooling fan and fan relays receive battery voltage from the underhood fuse block. The ground path for the operation of the cooling fan is provided at G104.

Conditions for Running the DTC

Conditions for Setting the DTC

P0480

The ECM detects an open in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

P0481

The ECM detects an open in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

P0691

The ECM detects a short to ground in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

P0692

The ECM detects a short to voltage in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

P0693

The ECM detects a short to ground in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

P0694

The ECM detects a short to voltage in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.

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.

Diagnostic Aids

When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. You should hear an audible click.
2. Ignition ON, command the appropriate cooling fan relay, or relays, ON and OFF with a scan tool. Observe the appropriate scan tool FC Relay Circuit Test Status parameters. The parameters should display OK or Not Run in each commanded state.
3. 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

1. Ignition OFF, disconnect all three cooling fan relays.

Note:  The following test must be performed on all three fan relay circuits.

2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:

•	Fan 1 relay and fan 2 relay terminal 85

•	S/P fan relay terminal 86

⇒	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.

Note:  The following test must be performed on all three fan relay circuits.

3. Test for 2.6-4.6 V between the ground and the relay coil control circuit terminal listed below:

•	Fan 1 relay and fan 2 relay terminal 86

•	S/P fan relay terminal 85

⇒	If less than the specified range, test the appropriate relay coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

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

Note:  The following test must be performed on all three fan relay circuits.

4. Connect a test lamp between B+ and the relay coil control circuit terminals listed below:

•	Fan 1 relay and fan 2 relay terminal 86

•	S/P fan relay terminal 85

5. Command the fan relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, replace the ECM.

6. If all circuits test normal, test or replace the relay.

Component Testing

1. Ignition OFF, disconnect the appropriate cooling fan relay.
2. Test for 200-240 Ω between terminals 85 and 86 of the relay.

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

3. Measure the resistance between the terminals listed below. The DMM should display O.L.

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the relay.

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

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

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.