G 2500 3/4 Ton Van V8-305 5.0L VIN M SFI (1997)
Electronic Brake Control Module: Description and Operation
DESCRIPTION
The Electronic Brake Control Module (EBCM) is part of the Electro-Hydraulic Control Unit (EHCU) assembly. The EBCM is the electronic
portion of the EHCU and its major function is to control the Brake Pressure Modulator Valve (BPMV). There are two serial data circuits used
with the EBCM. The first serial data circuit (CKT 799) is for ABS diagnostics only and is connected between the EBCM and Data Link Connector
(DLC). The-second serial data circuit (CKT 1807) is used to alert the Vehicle Control Module (VCM) of a rough road condition.
INPUTS/OUTPUTS
Inputs to the EBCM are three wheel speed signals, the stop lamp switch, differential pressure switch, ignition switch voltage, and unswitched
battery voltage.
Outputs of the EBCM are four isolation solenoids (internal to the EBCM), four dump solenoids (internal to the EBCM), the amber ANTILOCK
indicator lamp, the red BRAKE warning lamp and the pump motor.
OPERATION
The EBCM detects a rough road condition through the use of the wheel speed signals. The EBCM monitors the speed of each wheel. If any wheel
begins to approach lock-up, the EBCM controls the solenoids (isolation solenoid and dump solenoid) to reduce brake pressure to the wheel
approaching lock-up. Once the wheel regains traction, brake pressure is increased until the wheel again approaches lock-up. This cycle repeats
until either the vehicle comes to a stop, the brake is released or the wheel is no longer approaching lock-up.
SELF DIAGNOSTICS
The EBCM will also run "self diagnostics" to check for any system malfunctions. If the EBCM detects a malfunction with the system, it will
illuminate the amber ANTILOCK indicator to alert the driver of a malfunction. See: Antilock Brakes / Traction Control Systems/Testing and
Inspection
