Heated Glass Element

REAR DEFOGGER SWITCH SENSE CIRCUIT

Rear Defogger Switch Sense Circuit:

WHEN MONITORED
With the ignition on.

SET CONDITION
The Body Control Module (BCM) detects a short to power, ground, or an open on the Rear Defogger Switch Sense circuit.

POSSIBLE CAUSES
- Rear defogger switch sense circuit short to B(+)
- Rear defogger switch sense circuit short to ground
- Rear defogger switch sense circuit open
- A/C heater control module
- Body control module

DIAGNOSTIC TEST

1. REAR DEFOGGER SWITCH SENSE SHORTED TO B(+)




Turn the ignition off.
Disconnect the BCM C3 harness connector.

NOTE: Check connector - Clean/repair as necessary.

Turn the ignition on.
Measure the voltage of the Rear Defogger Switch Sense circuit at the BCM C3 harness connector.

Q: Is the voltage above 10.0 volts?

YES: Go to 5
NO: Go to 2

2. BODY CONTROL MODULE




With the ignition on.
Measure the voltage of the Rear Defogger Switch Sense circuit at the BCM C3 harness connector.Press and hold the Rear Defogger Switch.

Q: Is the voltage above 10.0 volts?

YES: Replace the Body Control Module. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 3

3. OPEN REAR DEFOGGER SWITCH SENSE CIRCUIT




Turn the ignition off.
Disconnect the A/C Heater Control Module harness connector.

NOTE: Check connector - Clean/repair as necessary.

Measure the resistance of the Rear Defogger Switch Sense circuit from the BCM C3 harness connector to the A/C Heater Control Module harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go to 4
NO: Repair the Rear Defogger Switch Sense circuit for an open. Perform BODY VERIFICATION TEST. Body Verification Test

4. REAR DEFOGGER SWITCH SENSE CIRCUIT SHORT TO GROUND




With the ignition off.
Measure the resistance between ground and the Rear Defogger Switch Sense circuit.

Q: Is the resistance below 100k ohms?

YES: Repair the Rear Defogger Switch Sense circuit for a short to ground. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Replace the A/C Heater Control Module. Perform BODY VERIFICATION TEST. Body Verification Test

5. REAR DEFOGGER SWITCH SENSE CIRCUIT SHORTED TO B(+)




Turn the ignition off.
Disconnect the A/C Heater Control Module harness connector.

NOTE: Check connector - Clean/repair as necessary.

Turn the ignition on.
Measure the voltage of the Rear Defogger Switch Sense circuit at the A/C Heater Control Module harness connector.

Q: Is the voltage above 1.0 volt?

YES: Repair the Rear Defogger Switch Sense circuit for a short to B(+). Perform BODY VERIFICATION TEST. Body Verification Test
NO: Replace the A/C Heater Control Module. Perform BODY VERIFICATION TEST. Body Verification Test