Normal Operation: Notes

The rear window defrost relay receives power from the battery junction box (BJB) fuse 35 (10A) on circuit (Y/GY). When the rear window defrost switch is pressed to the ON position, the HVAC module activates the rear window defrost relay by grounding circuit (W/O). When activated, the rear window defrost relay supplies 12 volts, to the rear window defrost grid on circuit (BR/Y). The rear window defrost grid is grounded through circuit (B/GY) to ground.

The HVAC module will deactivate the rear window defrost relay when one of the following conditions is met:

• The rear window defrost switch is pressed when feature is active.
• The ignition switch state is changed from ON to OFF/LOCK.
• The 15-minute timing function is complete.
• DTC B12BF - Heated backlight/mirror relay drive circuit open or shorted to ground, heated backlight and heated mirrors wire failure, relay drive circuit open or shorted to ground.