Brake Warning Indicator: Description and Operation

The red BRAKE warning 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 lamp illuminates when the ignition switch is moved from the OFF to the ON or CRANK position. This is done to check the bulb's operation.
Problems with this system will generally be of the type where the warning lamp fails to turn on when it should, or remains on when it should not.
The red BRAKE warning 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)
The brake fluid level switch is located in the brake fluid reservoir of the master cylinder assembly. The purpose of the switch is to provide the driver with an early warning that the brake fluid level in the master cylinder reservoir has dropped below an acceptable level.
As the fluid drops below the minimum level, the fluid level switch closes and grounds the red BRAKE warning lamp circuit. This turns on the red BRAKE warning 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 lamp can be turned on by the MIC in the case where the ABS is experiencing a problem where the amber ABS warning lamp needs to be illuminated and cannot. The MIC will then illuminate the red BRAKE warning lamp.