Test A

Pinpoint Test A: The Red Brake Warning Indicator Is Always On

Test A1-A4:

Test A5-A8:

Normal Operation
The red brake warning indicator is located in the instrument cluster and illuminates during prove-out, when the brake fluid in the brake master cylinder reservoir is below a specific level with the parking brake engaged. The instrument cluster receives a ground input on circuit 1309 (RD/YE) when the parking brake has been applied through circuit 1205 (BK), turning on the brake warning indicator. The smart junction box (SJB) provides a voltage reference signal to the brake master cylinder fluid level switch through circuit 1305 (DB) and back to the SJB on circuit 512 (TN/LG). When the brake fluid level is low, the brake fluid level switch closes to circuit 512 (TN/LG). The voltage reference signal the SJB is sending to the brake fluid level switch will drop to zero, then the SJB will send an SCP message to the instrument cluster to turn on the brake warning indicator.

Possible Causes
^ SJB DTC B2479 brake park switch circuit short to ground
^ SJB DTC C1189 brake fluid level sensor input circuit short to ground
^ low brake fluid level
^ brake fluid level switch
^ parking brake engaged
^ parking brake switch
^ circuit 512 (TN/LG) short to ground
^ circuit 1305 (DB) short to ground
^ circuit 1309 (RD/YE) short to ground
^ instrument cluster
^ SJB