VIN L
DTC P0495 (LGH)
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 P0495
- Cooling Fan Speed High
Diagnostic Fault Information
Circuit/System Description
The electro-viscous (EV) cooling fan clutch system enables the engine control module (ECM) to change the speed of the pulley driven cooling fan in relation to the engine speed. Ignition voltage is supplied directly to the fan clutch solenoid valve. The ECM uses two output drivers and a parallel circuit to directly control the EV fan clutch solenoid valve. The ECM controls the solenoid valve by pulse width modulating (PWM) the parallel control circuits to ground, with a solid state device called a driver. The ECM changes the cooling fan speed by increasing or decreasing the solenoid valve ON time, known as duty cycle.
Conditions for Running the DTC
* DTC P0016, P0112, P0113, P0117, P0118, P0335, P0336, P0340, P0341, P0480, P0483, P0526, P2228, or P2229 is not set.
* The engine is operating for greater than 10 seconds.
* The engine speed is greater than 1,071 RPM.
* The engine OFF time after the previous ignition cycle was greater than 0 seconds.
* The ambient air temperature (AAT) is warmer than -40°C (-40°F).
* The BARO is greater than 55 kPa.
* The ECM commanded fan clutch solenoid duty cycle is less than 36 percent.
* DTC P0495 runs continuously when the conditions above exist.
Conditions for Setting the DTC
* The cooling fan speed is greater than 1,500 RPM for greater than 80 seconds.
OR
* The clutch fluid pump-out, which is the time it takes for the fan clutch to disengage completely, is greater than a range of 10 minutes at sea level to 52 minutes at elevations of 6,500 ft.
Action Taken When the DTC Sets
DTC P0495 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0495 is a Type B DTC.
Reference Information
Schematic Reference
Engine Cooling Schematics (Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Cooling Fan Description and Operation (with RPO LMM) (Cooling Fan (with VIN 6)) Cooling Fan Description and Operation (W/LGH) (Cooling Fan Description and Operation (with VIN L))
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 (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition OFF, verify the fan clutch is not seized or binding.
2. Ignition ON, observe the DTC information with a scan tool. Verify DTC P0480, P0483, or P0526 is not set, if a DTC is set diagnose that DTC first.
3. Engine idling at operating temperature with all accessories turned OFF, for greater than 10 minutes.
Note: Depending on elevation above sea level it may take up to 52 minutes for the fan clutch to completely disengage.
4. Observe the scan tool DTC information. Verify DTC P0495 is not set.
• If the DTC is set, replace the cooling fan clutch assembly.
5. Engine at operating temperature, Operate the engine at 1,500 RPM for 2 minutes. Observe the DTC information with a scan tool. Verify DTC P0495 is not set.
• If the DTC is set, replace the cooling fan clutch assembly.
6. 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.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Fan Clutch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming