Test A: Red Brake Warning Indicator Always on

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

Normal Operation
The red brake warning indicator is located in the instrument cluster and illuminates when the brake fluid in the brake master cylinder reservoir is below a specific level, when the parking brake is engaged, or when there is a failure with the anti-lock brake system (ABS) electronic brake force distribution (EBD) system (the yellow ABS warning indicator will also illuminate). 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 fluid level switch through circuit 1305 (DB) and back to the SJB on circuit 128 (VT/YE). When the brake fluid level is low, the brake fluid level switch closes to circuit 128 (VT/YE). If the voltage reference signal the SJB is sending to the brake fluid level switch drops to zero, then the SJB sends a standard corporate protocol (SCP) message to the instrument cluster to turn on the brake warning indicator.

Possible Causes
^ low brake fluid level
^ brake fluid level switch
^ parking brake engaged
^ parking brake switch
^ circuit 128 (VT/YE) short to ground
^ circuit 1305 (DB) short to ground
^ circuit 1309 (RD/YE) short to ground
^ instrument cluster
^ SJB

Tests A1 - A2:

Tests A3 - A7:

PINPOINT TEST A: THE RED BRAKE WARNING INDICATOR IS ALWAYS ON