Test U: The Fog Lamps Are On Continuously

PINPOINT TEST U: THE FOG LAMPS ARE ON CONTINUOUSLY

U1-U3:

U4:

Normal Operation
The smart junction box (SJB) provides a reference signal to the fog lamp switch through circuit 1347 (DB/WH). When the fog lamp switch is engaged, the voltage signal is routed to ground through circuit 570 (BK/WH).

When the SJB detects the fog lamp switch has been pressed, the SJB provides a ground for the fog lamp relay coil through circuit 477 (LB/BK). When the fog lamp relay is energized, voltage is sent through circuit 478 (TN/OG) to the fog lamps.

Possible Causes
- Circuit 477 (LB/BK) short to ground
- Circuit 478 (TN/OG) short to voltage
- Fog lamp relay
- SJB