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P0480




DTC P0480 or P0481 (LUJ)

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 Instructionsprovides an overview of each diagnostic category.

DTC Descriptors
DTC P0480
- Cooling Fan Relay 1 Control Circuit Malfunction

DTC P0481
- Cooling Fan Relay 2 Control Circuit Malfunction

Diagnostic Fault Information






Circuit/System Description

The engine cooling fan system is composed of one fan, 5 relays, the engine control module (ECM), and the associated wiring. The fan assembly includes two resistors, which enable the fan to operate at 3 speeds.

Low Speed

In low speed operation, the ECM provides ground from ECM terminal 41 X1. The Cooling Fan Relay activates and provides ground to the Cooling Fan Low Speed Relay and the Cooling Fan Speed Control Relay. The Cooling Fan Low Speed Relay activates and provides B+ to the cooling fan motor through cooling fan resistor terminal 2.

Medium Speed

In medium speed operation, the ECM provides ground from ECM terminal 54 X1. The Cooling Fan Medium Speed Relay activates and provides power to the cooling fan motor through cooling fan resistor terminal 3.

High Speed

In high speed operation, the ECM provides ground from ECM terminals 41 X1 and 54 X1. 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 Cooling Fan High Speed Relay. The Cooling Fan High Speed Relay activates and provides power to the cooling fan motor, bypassing the cooling fan resistor.

Conditions for Running the DTC

* The engine is running.
* The ignition voltage is between 11-18 V.
* The engine speed is greater 400 RPM.
* These DTCs run continuously once the above conditions 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 2 s.

Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0480 and P0481 are Type C DTCs.

Reference Information
Schematic Reference

Engine Cooling Schematics [1][2]Electrical Diagrams
Connector End View Reference

Component Connector End Views Sunshade - Left (D6I)
Description and Operation

Cooling System Description and Operation (LDE, LLU, LXV, 2H0 LUW and LFH) Description and OperationCooling System Description and Operation (1.4L LUH, LUJ, and LUV) 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

Scan Tool Reference

Control Module References Control Module Referencesfor scan tool information

Circuit/System Verification

1. Ignition ON, command the appropriate KR20D Cooling Fan High Speed Relay, KR20F Cooling Fan Relay, or KR20P Cooling Fan Medium Speed Relay ON and OFF with a scan tool. You should hear the relay click when commanded ON and OFF.
2. 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 the relays listed below:

* KR20D Cooling Fan High Speed Relay
* KR20F Cooling Fan Relay
* KR20P Cooling Fan Medium Speed Relay

2. Ignition ON, verify that a test lamp illuminates between the circuit terminals listed below and ground:

* KR20F Cooling Fan Relay ignition circuit terminal 85
* KR20P Cooling Fan Medium Speed Relay ignition circuit terminal 1

• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

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

* KR20D Cooling Fan High Speed Relay terminal 2
* KR20F Cooling Fan Relay terminal 86
* KR20P Cooling Fan Medium Speed Relay terminal 2

4. Command the Cooling Fan Relay 1 and Cooling Fan Relay 2 ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states for the appropriate relay.

• If the test lamp is always ON, test the coil control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
• If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

5. Connect the KR20F Cooling Fan Relay.
6. Command the Cooling Fan Relay 1 ON and OFF with a scan tool and verify the DTC does not reset.

• If the DTC resets, test or replace the KR20F Cooling Fan Relay and verify the DTC does not reset. If the DTC resets, replace the K20 Engine Control Module.

7. Connect the KR20P Cooling Fan Medium Speed Relay.
8. Command the Cooling Fan Relay 2 ON and OFF with a scan tool and verify the DTC does not reset.

• If the DTC resets, test or replace the KR20P Cooling Fan Medium Speed Relay and verify the DTC does not reset. If the DTC resets, replace the K20 Engine Control Module.

9. If all circuits test normal, test or replace the KR20D Cooling Fan High Speed Relay.

Component Testing

Relay Test
1. Ignition OFF, disconnect the relays listed below:

* KR20D Cooling Fan High Speed Relay
* KR20F Cooling Fan Relay
* KR20P Cooling Fan Medium Speed Relay

2. Measure for 70-110 ohm between terminals 85 or 1 and 86 or 2.

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

3. Measure for infinite resistance between following terminals:

* Terminals 30 or 3 and 86 or 2
* Terminals 30 or 3 and 87 or 5
* Terminals 30 or 3 and 85 or 1
* Terminals 85 or 1 and 87 or 5

• If not the specified value, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Control Module References Control Module Referencesfor ECM replacement, programming and setup

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