Test A: The Red Brake Warning Indicator Is Always On

Test A: The Red Brake Warning Indicator is Always On

Refer to Vehicle/Diagrams, Instrument Cluster for schematic and connector information.

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 or when the parking brake is engaged. When the parking brake is applied, the instrument cluster receives a ground input on circuit 1309 (RD/YE) through the parking brake switch and circuit 1205 (BK), turning on the brake warning indicator. The smart junction box (SJB) provides a voltage to the brake fluid level switch through circuit 547 (LG/YE) and back through the SJB return circuit 512 (TN/LG). When the brake fluid level is low, the brake fluid level switch closes and connects circuit 547 (LG/YE) to circuit 512 (TN/LG). The voltage reference signal the SJB is sending to the brake fluid level switch drops to zero, then the SJB sends a message over the medium speed communication area network (MS-CAN) to the instrument cluster to turn on the brake warning indicator.

Possible Causes
- Circuit shorted
- Low brake fluid level
- Brake fluid level switch
- Parking brake engaged
- Parking brake switch
- Instrument cluster
- SJB

CAUTION: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

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