Brake Warning Lamp Circuit Operation

CIRCUIT OPERATION
The brake warning lamp is used to alert the operator of a problem in the vehicles braking system. This lamp also illuminates when the ignition switch is turned to the START position to perform a self check.

Power for the lamp is supplied on circuit F11. This circuit is HOT when the ignition switch is in the OFF (unlock), START, and RUN positions. The F11 circuit is protected by a 5 Amp fuse located in cavity 17 of the junction block.

There are two switches used in this system and they are wired in parallel form. A parking brake switch. located on the parking brake mechanism, will illuminate the lamp if the normally OPEN switch is CLOSED. This switch is case grounded.

The second switch used is the brake warning lamp switch. This switch in normally OPEN. When the brake system pressure is below the predetermined level the switch CLOSES and completes a path to ground.

The G9 circuit is used to connect the switches to the cluster. Grounding for the brake warning lamp switch is completed on the Z1 circuit which terminates at the left front frame rail.

If the vehicle is built for sale in Canada the parking brake switch is used for the Daytime Running Lamp (DRL) system. Description and Operation

On vehicles equipped with anti-lock brakes the operation of the warning lamp is controlled by the ABS control module.