Normal Operation
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The rear window defrost relay receives power from the battery junction box (BJB) fuse 23 (40A) on circuit 185 (BK). When the rear window defrost switch is pressed to the ON position, a ground is supplied to the smart junction box (SJB) on circuit 1010 (DB/OG), through the rear window defrost switch, then through circuit 570 (BK/WH). Upon receipt of the ground, the SJB activates the rear window defrost relay, which then supplies 12 volts to the rear window defrost grid on circuit 186 (BN/LB) and circuit 186 (BK). The rear window defrost grid is grounded through circuit 57 (BK) to ground.
Possible Causes
- Circuit 59 (DG/VT) short to voltage
- Circuit 186 (BN/LB)/circuit 186 (BK) short to voltage
- Circuit 1010 (DB/OG) short to ground
- Rear window defrost relay
- Rear window defrost switch
- SJB