P0480
DTC P0480
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 provides an overview of each diagnostic category.
DTC Descriptor
DTC P0480
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Cooling Fan Speed Output Circuit
Diagnostic Fault Information
Circuit/System Description
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan speed control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the pulse width modulated signal. The cooling fan speed is affected by many different conditions and can be adjusted from 10-90 percent duty cycle. Ninety percent is considered high fan speed. When multiple cooling speed requests are received, the ECM uses the highest cooling fan speed of all the requests. During normal fan ON operation, the control circuit voltage will be low and near battery voltage when the fan is OFF.
Conditions for Running the DTC
* The ignition voltage is between 11-18 volts.
* The engine speed is greater than 400 RPM.
* DTC P0480 runs continuously when the conditions above are met.
Conditions for Setting the DTC
P0480
The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.
Reference Information
Schematic Reference
Engine Cooling Schematics [1][2]Cooling System
Connector End View Reference
Component Connector End Views Folding Top 5 Bow Lowered Switch (CM7)
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
Special Tools
J 35616-200 - Test Lamp Kit
Circuit/System Verification
Note:
There is a slight delay before the cooling fan activates.
1. Engine operating, command the cooling fan speed from 0-100 percent with a scan tool. The fan speed should transition with each commanded state.
2. Observe the DTC information with a scan tool. DTC P0480 should set.
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 the connector from the cooling fan speed control module.
2. Connect a test lamp between the cooling fan speed control module ground circuit terminal B and B+. The test lamp should illuminate.
• If the test lamp does not illuminate, test the ground circuit for open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal C 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+ fuse open, test or replace the cooling fan and motor assembly.
Note:
Use the J 35616-200 - Test Lamp for this test. If the J 35616-200 - Test Lamp is not available, use a test lamp that measures greater than 20 ohms.
4. Ignition ON, connect a test lamp between the cooling fan speed control circuit terminal A and B+. The test lamp should not illuminate.
• If the lamp is ON, test the cooling fan speed control circuit for a short to ground. If the circuit tests normal, replace the ECM.
5. Ignition ON, command the cooling fan speed to 50 percent with a scan tool. The test lamp should illuminate and flash.
• If the test lamp does not illuminate, test the cooling fan speed control circuit for a short to voltage or for an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all of the circuits test normal, replace the cooling fan control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Fan Control Module Replacement Service and Repair
* Control Module References Control Module References