K 3500 Truck 4WD V8-454 7.4L VIN J SFI (1996)
Brake Warning Indicator: Description and Operation
Battery voltage is applied through the GAGES FUSE 4 to the "BRAKE" Indicator when the Ignition Switch is in the RUN, BULB TEST or START
positions. The "BRAKE" Indicator can be lit by having ground applied to it from any of three switches or the Antilock Brake Module.
The "BRAKE" Indicator will light whenever the Parking Brake is engaged. When the Parking Brake is engaged, ground is supplied through the closed
contacts of the Parking Brake Warning Switch to the "BRAKE" Indicator. The "BRAKE" Indicator lights to alert the driver that the Parking Brake is
engaged.
The "BRAKE" Indicator will light when the Ignition Switch is turned from the "LOCK" to the RUN position. This is when the Antilock Brake Module
conducts its initial test which entails lighting the "BRAKE" Indicator and the ABS Indicator. The Antilock Brake Module will also light the "BRAKE"
Indicator if there is a malfunction within the Four Wheel Antilock Brake System which is affecting the operation of the base Hydraulic Braking system.
The "BRAKE" Indicator will light if there is low Brake fluid pressure in the front or rear Brakes. When the Combination Valve senses low Brake fluid
pressure in the front or rear brakes it closes the Brake Pressure Warning Switch. A ground is supplied through the closed contacts of the Brake Pressure
Warning Switch to the "BRAKE" Indicator. With both power and ground applied to the "BRAKE" Indication it will light.
The "BRAKE" Indicator will also light whenever the Ignition Switch is turned to the BULB TEST position.
The Daytime Running Lamps Module senses ground through the Park Brake Warning Switch. When this input is grounded, the Daytime Running Lamps
are not energized. Diode D202 prevents Anti-Lock Brake Module or Brake Pressure Warning Switch operation from turning off the Daytime Running
Lamps.
The "BRAKE" Indicator will also light whenever the Ignition Switch is turned to the BULB TEST Position.
