• | 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. |
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 | -- |
|
The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.
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.
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 right cooling fan operating at a reduced 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.
• | The ignition voltage is between 8-18 volts. |
• | The engine speed is more than 40 RPM. |
• | The ECM driver transitions from ON to OFF or from OFF to ON. |
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.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
Cooling Fan Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | 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. |
⇒ | If less than the specified range, test the appropriate relay coil control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the K20 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 K20 ECM. |
⇒ | If the test lamp is always OFF, replace the K20 ECM. |
⇒ | If the not within the specified range, replace the relay. |
• | 2 and 6 |
• | 2 and 8 |
• | 2 and 4 |
• | 4 and 8 |
⇒ | If not the specified range, replace the relay. |
⇒ | If greater than the specified range, replace the relay. |
Note: This step is only for the KR20E cooling fan speed control relay.
⇒ | If greater than the specified range, replace the relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |
• | 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. |
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 | -- |
|
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 | -- |
|
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 | -- |
|
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 | -- |
|
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 | -- |
|
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 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.
• | 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. |
The ECM detects an open on the low speed cooling fan relay control circuit for more than 1 second.
The ECM detects an open circuit on the high speed cooling fan relay control circuit for more than 1 second.
The ECM detects a short to ground on the low speed cooling fan relay control circuit for more than 1 second.
The ECM detects a short to voltage on the low speed cooling fan relay control circuit for more than 1 second.
The ECM detects a short to ground on the high speed cooling fan relay control circuit for more than 1 second.
The ECM detects a short to voltage on the high speed cooling fan relay control circuit for more than 1 second.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
Cooling Fan Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | If the fan does not operate correctly, go to low speed operation malfunction. |
⇒ | If the fan does not operate correctly, go to medium speed operation malfunction. |
⇒ | If the fan does not operate correctly, go to high speed operation malfunction. |
Note: Circuit/System Verification must be performed before Circuit/System Testing or misdiagnosis may result.
• | KR20B Cooling Fan Medium Speed 2 Relay |
• | KR20E Cooling Fan Speed Control Relay |
• | KR20F Cooling Fan Relay |
• | 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. |
⇒ | If greater than the specified range, test the output circuit for an open/high resistance. |
• | 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. |
⇒ | 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 |
⇒ | 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. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | 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. |
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM. |
⇒ | If not within the specified range, replace the relay. |
⇒ | If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM. |
⇒ | If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM. |
• | KR20B Cooling Fan Medium Speed 1 Relay |
• | KR20F Cooling Fan Relay |
⇒ | If the test lamp illuminates, test the output circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
⇒ | 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. |
⇒ | 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. |
⇒ | If not within the specified range, replace the KR20A Cooling Fan Medium Speed 1 Relay. |
⇒ | If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM. |
⇒ | If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM. |
• | KR20D Cooling Fan High Speed Relay |
• | KR20E Cooling Fan Speed Control Relay |
⇒ | If the test lamp illuminates, test the output circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the ignition circuit terminal for an open/high resistance. |
⇒ | 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. |
⇒ | 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. |
• | 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. |
• | KR20D Cooling Fan High Speed Relay |
• | KR20E Cooling Fan Speed Control Relay |
⇒ | If the resistance is not within the specified range, replace the relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If not the specified value, replace the relay. |
⇒ | If more than the specified value, replace the relay. |
⇒ | If more than the specified value, replace the relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |
• | 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. |
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 | -- |
|
The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.
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.
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.
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.
• | 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. |
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.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
Cooling Fan Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | 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. |
⇒ | If not within the specified range, replace the relay. |
Note: Perform the remainder of this procedure for each of the appropriate relays.
⇒ | If greater than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM. |
⇒ | 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 the not within the specified range, replace the relay. |
• | 2 and 6 |
• | 2 and 8 |
• | 2 and 4 |
• | 4 and 8 |
⇒ | If not the specified range, replace the relay. |
⇒ | If greater than the specified range, replace the relay. |
Note: This step is only for the KR20E cooling fan speed control relay.
⇒ | If greater than the specified range, replace the relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |