P0480

DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LEA)

Diagnostic Instructions

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

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

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptors

DTC P0480
- Cooling Fan Relay 1 Control Circuit

DTC P0481
- Cooling Fan Relays 2 and 3 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 Relays 2 and 3 Control Circuit Low Voltage

DTC P0694
- Cooling Fan Relays 2 and 3 Control Circuit High Voltage

Diagnostic Fault Information






Circuit/System Description

The engine cooling fan system is composed of one cooling fan, a series of 3 relays, the engine control module (ECM), and the associated wiring. The cooling fan motor assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits. The underhood fuse block supplies the cooling fan relays with B+ at the switch side, and ignition voltage at the coil side of the relays through separate fuses. When the cooling fan is commanded ON, the ECM grounds the appropriate relay control circuit, which energizes the relay coil. The magnetic field, created within the relay by the energized relay coil, overcomes the spring tension of the bi-metal switch armature causing the relay switch to close. When the relay switch closes, B+ is supplied to the cooling fan motor through the relay controlled output circuit, causing the cooling fan motor to operate. A dedicated ground is supplied to the cooling motor to complete the circuit.

Conditions for Running the DTC

2H0, LDD, LDE, LLU - ECM with 2 Face Mounted Connectors

* The ignition voltage is between 11-32 volts.

* The engine speed is 400 RPM or greater.

* The ECM has commanded the output driver ON and OFF at least once during the ignition cycle.

* DTCs P0480 and P0481 run continuously when the conditions above are met.

LDD, LDE, LEA, LHU, LUJ - ECM with 3 Face Mounted Connectors

* The ignition voltage is 11 volts or greater.

* The ECM has commanded the output driver ON and OFF at least once during the ignition cycle.

* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

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 5 seconds.

Action Taken When the DTC Sets

* DTCs P0480 or P0481 are Type C DTCs - 2H0, LDD, LDE, LLU

* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type C DTCs - LDD, LDE, LUJ

* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs - LEA, LHU

Conditions for Clearing the MIL/DTC

* DTCs P0480 or P0481 are Type C DTCs - 2H0, LDD, LDE, LLU

* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type C DTCs - LDD, LDE, LUJ

* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs - LEA, LHU

Diagnostic Aids

* The scan tool cooling fan output control operates as follows:

- Cooling Fan Relay 1 operates the fan at a low speed

- Cooling Fan Relay 2 and 3 operates the fan at a medium speed

- Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed

* When disconnecting 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 Heating/Cooling Schematics [1][2]Cooling System

Connector End View Reference

Component Connector End Views Outside Rearview Mirror - Driver

Description and Operation

Cooling Fan Description and Operation (LEA) Cooling Fan Description and OperationCooling Fan Description and Operation (LHU) Cooling Fan Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fan ON and OFF with a scan tool.

• If a click is not heard or felt at each of the relays
Refer to Circuit/System Testing.

• If a click is heard or felt at each of the relays

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.

4. Verify the DTC does not set.

• If the DTC sets
Refer to Circuit/System Testing.

• If the DTC does not set

5. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect all cooling fan relays, ignition ON.

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

2. Verify that a test lamp illuminates between ground and a relay coil ignition circuit terminals listed below:

* KR20C Cooling Fan Low Speed Relay terminal 86

* KR20D Cooling Fan High Speed Relay terminal 86

* KR20P Cooling Fan Medium Speed Relay terminal 86

• If the test lamp does not illuminate and the fuse is good

1. Ignition OFF, remove the test lamp.

2. Test for less than 2 ohms in the ignition circuit of the appropriate cooling fan relay, end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF, remove the test lamp.

2. Test for infinite resistance between the cooling fan relay ignition circuits and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the appropriate cooling fan relay.

• If the test lamp illuminates

3. Remove the test lamp.

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

4. Connect a DMM, set on the diode setting, between ground and a relay control circuit terminal listed below:

* KR20C Cooling Fan Low Speed Relay terminal 85

* KR20D Cooling Fan High Speed Relay terminal 85

* KR20P Cooling Fan Medium Speed Relay terminal 85

5. Verify the DMM reading is greater than 2 V or displays O.L with the Cooling Fan Relays commanded OFF.

• If 2.5 V or less

1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the appropriate relay coil control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the K20 Engine Control Module.

• If greater than 2.5 V or displays O.L.

6. Command the cooling fan ON at high speed with a scan tool.

7. Verify the DMM reading is less than 1 V at the cooling fan relay terminals listed below:

* KR20C Cooling Fan Low Speed Relay terminal 85

* KR20D Cooling Fan High Speed Relay terminal 85

* KR20P Cooling Fan Medium Speed Relay terminal 85

• If 1 V or greater

1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON.

2. Test for less than 1 V between the appropriate cooling fan relay control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V.

3. Ignition OFF.

4. Test for less than 2 ohms in the appropriate cooling fan relay control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K20 Engine Control Module.

• If less than 1 V

8. Test or replace the appropriate cooling fan relay.

Component Testing

1. Ignition OFF.

2. Disconnect the appropriate cooling fan relay.

3. Test for 65-105 ohms between terminals 85 and 86.

• If less than 65 ohms or greater than 105 ohms
Replace the cooling fan relay.

• If between 65-105 ohms

4. Test for infinite resistance between the following terminals:

* 30 and 86

* 30 and 87

* 30 and 85

* 85 and 87
OR

* 3 and 2

* 3 and 5

* 3 and 1

* 1 and 5

• If less than infinite resistance
Replace the appropriate cooling fan relay.

• If infinite resistance

5. Install a 20 A fused jumper wire between relay terminal 86 and B+.

6. Install a jumper wire between relay terminal 85 and ground.

7. Test for less than 2 ohms between terminals 30 and 87.

• If 2 ohms or greater
Replace the cooling fan relay.

• If less than 2 ohms

8. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)

* Control Module References Control Module References for ECM replacement, programming, and setup.