Test B: The Control Illumination Is Inoperative

PINPOINT TEST B: THE CONTROL ILLUMINATION IS INOPERATIVE

B1-B5:

B6-B7:

Normal Operation
The instrument cluster monitors the medium-speed controller area network (MS-CAN) bus on circuits 1848 (PK/OG) and 1847 (WH/OG) for a PARKING LAMPS ON or HEADLAMPS ON message. The PARKING LAMPS ON or HEADLAMPS ON message is generated by the smart junction box (SJB). When the instrument cluster detects a HEADLAMPS ON message, it sends a variable voltage to the module-controlled illumination sources through circuit 19 (LB/RD). The module-controlled illumination sources are grounded through circuit 57 (BK).

Possible Causes
- Circuit 19 (LB/RD) open, short to ground or voltage
- Circuit 170 (RD/LB) short to voltage
- Instrument cluster
- SJB