Diagnostic Routine E

Diagnostic Routine E

Diagnostic Overview

The Defrost System is Inoperative

Refer to Wiring Diagram Set 56 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

REFER to Rear Window Defrost for normal system operation.

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Verify that BJB (Battery Junction Box) fuses 26 (40A) and 93 (5A) are OK.

- Visually inspect the rear window defrost relay.

- Visually inspect the rear window defrost grid and electrical connectors for damage.

Pinpoint Test

1. CHECK THE REAR WINDOW DEFROST GRID VOLTAGE

1. Disconnect: Rear Window Defrost Grid C402A.

2. Start the engine.

3. Activate the rear defrost switch.

4. Measure:





Is the voltage greater than 11 volts?








2. CHECK THE REAR WINDOW DEFROST GRID GROUND

1. Ignition OFF.

2. Disconnect: Rear Window Defrost Grid C402B.

3. Measure:





Is the resistance less than 3 ohms?








3. CHECK THE VOLTAGE SUPPLY TO THE REAR WINDOW DEFROST RELAY

1. Ignition OFF.

2. Disconnect: Rear Window Defrost Relay.

3. Ignition ON.

4. Measure:





Are the voltages greater than 11 volts?








4. CHECK THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE OUTPUT

NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

1. Start the engine.

2. Activate the rear window defrost switch.

3. Measure:





Does the test light illuminate?








5. CHECK THE REAR WINDOW DEFROST RELAY

1. Carry out the rear window defrost relay component test.

Did the rear window defrost relay pass the component test?








6. CHECK THE REAR DEFROST SWITCH (CC_SW_R_DEF) PID

1. Ignition ON.

2. Using a scan tool, view FCIM (Front Controls Interface Module) PIDs (Parameter Identifications).

3. Monitor the FCIM (Front Controls Interface Module) PID (Parameter Identification) CC_SW_R_DEF while pressing and releasing the rear window defrost switch.

Does the PID (Parameter Identification) agree with the rear window defrost switch status?








7. CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C228A.

3. Measure:





Is the resistance less than 3 ohms?








8. CHECK FOR CORRECT HVAC (Heating, Ventilation, and Air Conditioning) MODULE OPERATION

1. Inspect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors.

2. Repair:

- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins as necessary
- pushed-out-pins - install new pins as necessary

3. Reconnect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors. Make sure they seat and latch correctly.

4. Reconnect all previously disconnected components and system electrical connectors.

5. Operate the system and determine if the concern is still present.

Is the concern still present?