Brake Warning Indicator: Description and Operation

RED BRAKE WARNING INDICATOR
The red BRAKE warning indicator lamp is located in the instrument panel cluster and illuminates when a low brake fluid condition occurs or when the parking brake lever is applied with the ignition key in the ON position. In addition, the red BRAKE warning indicator lamp illuminates when the ignition switch is moved from the OFF to the ON or CRANK position. This is done to check the LED's operation. The red brake warning indicator can also be turned on if the CAB indicates an Electronic Brake Distribution (EBD) failure.

Problems with this system will generally be of the type where the warning indicator lamp fails to turn ON when it should, or remains ON when it should not.

The red BRAKE warning indicator lamp LED is supplied with current anytime the ignition switch is ON. The bulb is illuminated by completing the ground circuit using any of the following components:
- The brake fluid level switch located in the master cylinder reservoir
- The parking brake switch mounted on the parking brake lever
- The ignition switch when the ignition switch is first moved to the ON or CRANK position
- The Mechanical Instrument Cluster (MIC) (with ABS)
- The ABS Electronic Brake Distribution (EBD)

As the fluid drops below the minimum level, the brake fluid level switch in the brake fluid reservoir closes and grounds the red BRAKE warning indicator lamp circuit. This turns on the red BRAKE warning indicator lamp. At this time, the master cylinder fluid reservoir must be checked and filled to the full mark with DOT 3 brake fluid. An abnormal loss of brake fluid in the master cylinder fluid reservoir could be caused by a leak in the hydraulic system. The entire brake hydraulic system should be checked for evidence of a leak.

The red BRAKE warning indicator lamp can be turned ON by the MIC in the case where the ABS is experiencing a problem where the amber ABS warning indicator lamp needs to be illuminated and cannot. The MIC will then illuminate the red BRAKE warning indicator lamp.