GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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.

DTC Descriptor

DTC P0483: Cooling Fan System Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Cooling Fan Relay Ground

--

P0483

--

--

Cooling Fan Relay Voltage Supply

P0480, P0483

P0480, P0483

--

--

Cooling Fan Relay Control

P0480

P0480

--

--

Hall Effect Sensor Low Reference

--

P0483, P0526

--

--

Hall Effect Sensor 5-Volt Reference

P0642

P0526

P0401, P0643

--

Hall Effect Sensor Cooling Fan Speed Signal

P0526

P0526

P0526

--

Cooling Fan Clutch Fluid Solenoid Valve Ground

--

P0483

--

--

Cooling Fan Clutch Control

P0483

P0483

P0483, P0495

--

Circuit/System Description

The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan clutch through the cooling fan clutch supply voltage circuit. The control module uses this PWM signal in order to control the speed of the cooling fan clutch. The signal controls the position of the oil control valve inside the cooling fan clutch.

Conditions for Running the DTC

    • The engine is running.
    •  DTCs P0480 and P0526 are not set.
    • The engine speed is not changing more than 250 RPM for 5 seconds.
    •  The fan command is greater than 0 percent.

Conditions for Setting the DTC

The difference between the commanded and the actual cooling fan speed is greater than 500 RPM for 30 seconds.

Action Taken When the DTC Sets

DTC P0483 is a Type C DTC.

Conditions for Clearing the DTC

DTC P0483 is a Type C DTC.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

    •  Cooling System Connector End Views
    •  Engine Control Module Connector End Views for the 6.6L (LMM) engine

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

  1. Ignition OFF, inspect the cooling fan and the drive belt for the following conditions:
  2. • A cracked drive belt
    • A loose or a worn drive belt
    •  A misrouted drive belt
    •  Oil leaks at the cooling fan clutch
    •  A free-spinning cooling fan
    • A seized cooling fan clutch
    • A broken cooling fan
  3. Idle the engine.
  4. Command the cooling fan clutch to 10 percent.
  5. Operate the engine at 1,500 RPM for 2 minutes. The fan should be quiet to indicate the clutch is disengaged.
  6. Command the cooling fan clutch to 80 percent.
  7. Operate the engine at 1,500 RPM for 2 minutes. The difference between the fan speed and the desired fan speed should remain less than 1,000 RPM throughout the speed transition.

Circuit/System Testing

  1. Ignition OFF, disconnect the fan relay.
  2. Measure between the fan relay ground circuit terminal K9 and ground for less than 3 ohms.
  3. If more than the specified range, test the ground circuit for an open/high resistance.
  4. Operate the engine at 1,500 RPM for 2 minutes. The fan should be quiet to indicated the clutch is disengaged.
  5. If not disengaged, test the cooling fan clutch supply voltage circuit for a short to voltage. If the circuit tests normal, replace the clutch.
  6. Ignition OFF, install a 10A fused jumper wire between the positive terminal at the battery and the cooling fan clutch supply voltage circuit terminal B.
  7. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicated the clutch is engaged.
  8. If not engaged, test the cooling fan clutch supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the clutch.
  9. Ignition OFF, install a 10A fused jumper wire between the relay voltage supply circuit terminal J12 and the cooling fan clutch supply voltage circuit terminal.
  10. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicated the clutch is engaged.
  11. If not engaged, test the relay voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.
  12. Connect a test lamp between the positive terminal at the battery and the cooling fan clutch relay control circuit terminal L12.
  13. Engine RUNNING at 1,500 RPM, command the cooling fan clutch to 80 percent for 2 minutes. The test lamp should turn on steady or flash, indicating that the control module can control the relay.
  14. If the lamp does not flash or turn on steady, test the cooling fan clutch control circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the control module.
    If the lamp does not flash or vary correctly, test the cooling fan clutch control circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the control module.
  15. Perform the relay component test. The relay should test normal.
  16. If the relay does not test normal, replace the relay.
  17. Ignition OFF, disconnect the fan clutch harness at the shroud.
  18. Measure between the low reference circuit terminal C and ground for less than 3 ohms.
  19. If more than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.
  20. Ignition ON, measure between the 5-volt reference circuit terminal E and the low reference circuit terminal C for 4.8-5.2 volts.
  21. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module.
    If more than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module.
  22. Install jumper wires in the 5-volt reference and low reference circuits between the harness and pigtail connectors at the shroud.
  23. • 5-volt reference circuit terminal E
    • Low reference circuit terminal C
  24. Measure DC voltage between the signal circuit terminal D at the sensor pigtail connector and the 5-volt reference circuit jumper wire terminal.
  25. Ignition ON, rotate the fan by hand. The voltage should toggle between approximately 5 volts and 0 volts.
  26. If the voltage does not toggle correctly, test the three circuits in the pigtail harness for a short to ground, a short to voltage, or an open/high resistance. If the circuits test normal, replace the clutch.
  27. Leave the jumpers from the previous step in place. Measure voltage between the signal circuit terminal D of the harness and pigtail connectors at the shroud.
  28. Rotate the fan by hand. The voltage should toggle between approximately 5 volts and 0 volts.
  29. If the voltage does not toggle correctly, test the signal circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the control module.
  30. If all circuits, the relay, and the speed sensor test normal, replace the clutch.

Component Testing

Relay Test

  1. Connect the relay ground terminal to ground and the voltage supply terminal to appropriately fused power to energize the relay.
  2. Test for less than 1 volt between the load voltage supply terminal and ground.
  3. Connect the relay control circuit terminal to ground.
  4. Test for B+ between the load voltage supply terminal and ground.

Repair Instructions

Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fan Clutch Replacement
    •  Control Module References for replacement, setup, and programming