B0285

DTC B0285

CIRCUIT DESCRIPTION




The body control module (BCM) monitors the rear defogger switch input. When the rear defogger is turned on, rear defog switch closed, the BCM grounds the coil side of the rear defog relay. This will energize the relay activating the rear defogger.

The first time in an ignition cycle that the rear defogger is activated, the rear defogger will remain on for 15 minutes, or until the ignition switch is turned OFF. If the rear defogger is activated again during the same ignition cycle, the rear defogger will remain on for 7.5 minutes, or until the ignition switch is turned OFF.

CONDITIONS FOR RUNNING THE DTC
The ignition is in RUN.

CONDITIONS FOR SETTING THE DTC
- The BCM detects an open or short to ground in the rear defog relay control circuit when the relay is energized.
- The condition exists for 30 seconds.
- The BCM is not requesting the rear defogger system.

ACTION TAKEN WHEN THE DTC SETS
- The rear window defogger will be disabled until the condition is no longer present.
- The LED on the defogger switch will not illuminate when pressed.

CONDITIONS FOR CLEARING THE DTC
- This DTC will change from current to history when the fault is no longer present.
- A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

TEST DESCRIPTION

Steps 1-11:

Step 12:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the REAR DEFOG relay operates. Command both the on and off states. Repeat the commands as necessary.
3. Verifies that the BCM is providing ground input to the REAR DEFOG relay.
5. Tests for a short to ground on the rear defog relay control circuit of the REAR DEFOG relay coil.