P0495

DTC P0495

Diagnostic Instructions

^ Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
^ Review Strategy Based Diagnosis for an overview of the diagnostic approach.
^ 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 cooling fan relay sends a pulse width modulation (PWM) signal (12-14 volts) to the cooling fan by the cooling fan clutch supply voltage circuit. The control module uses the PWM signal, which controls the speed of the cooling fan clutch by controlling the position of the oil control valve inside the clutch. If the cooling fan clutch RPM is to high when the control module is commanding 0 percent, DTC P0495 will set.

Conditions for Running the DTC

^ The engine is running.
^ The system voltage is greater than 8.5 volts.
^ The intake air temperature (IAT) is greater than -7°C (+19°F).
^ Zero percent duty cycle is commanded, and the engine RPM has been over 1,800 RPM for at least 120 seconds.

Conditions for Setting the DTC

Cooling fan RPM exceeds 1,600 RPM for 81 seconds.

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

Connector End View Reference

^ Cooling System Connector End Views
^ Powertrain Control Module Connector End Views for 4.2L
^ Engine Control Module Connector End Views for 5.3L
^ Engine Control Module Connector End Views for 6.0L

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs
^ Electrical Center Identification Views

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

Engine OFF, verify the fan clutch is not binding by turning the fan by hand.

Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the fan shroud.
2. Operate the engine at 2,000 RPM for 2 minutes. The fan should be quiet to indicate the clutch is disengaged.
^ If disengaged, test or replace the relay.
^ If not disengaged, test the cooling fan clutch supply voltage circuit for a short to voltage. If the circuit tests 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

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

^ Fan Clutch Replacement
^ Cooling Fan and Shroud Replacement
^ Cooling Fan Relay Replacement
^ Control Module References for replacement, setup, and programming