Test U: The Fog Lamps Are Inoperative

PINPOINT TEST U: THE FOG LAMPS ARE INOPERATIVE

U1-U5:

U5-U7:

U8-U10:

U10-U13:

U13-U15:

Normal Operation
The smart junction box (SJB) sends 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. Voltage to the fog lamp relay is provided through circuit 554 (YE/BK).

Possible Causes
- Fuse
- Circuit 477 (LB/BK) open
- Circuit 478 (TN/OG) open
- Circuit 554 (YE/BK) open
- Circuit 570 (BK/WH) open
- Circuit 1347 (DB/WH) open, or short to ground
- Fog lamp relay
- Fog lamp switch
- SJB