Envoy 2WD V6-4.3L VIN W (1998)
Electronic Brake Control Module: Description and Operation
The Electronic Brake Control Module (EBCM) is part of the Electro-Hydraulic Control Unit (EHCU). The EBCM is the electronic portion of the
EHCU. The major function of the EBCM is to control the BPMV. Inputs to the EBCM include the following items:
^
Three wheel speed sensors
^
Stop Lamp Switch
^
Differential pressure
^
Ignition switch voltage
^
Unswitched battery voltage
Outputs of the EBCM include the following items:
^
Three isolation solenoids (internal to the EHCU)
^
Three dump solenoids (internal to the EHCU)
^
The amber ABS indicator lamp
^
The red BRAKE warning lamp
^
The pump motor
A diagnostic serial data line (ABS only) is also used for diagnostic service tools and assembly plant testing.
The EBCM monitors the speed of each wheel. If any wheel approaches lockup, the EBCM controls the solenoids (isolation solenoid and dump
solenoid) in order to reduce brake pressure to the wheel approaching lockup. Once the wheel regains traction, brake pressure is increased until the
wheel again approaches lockup. This cycle repeats until either the vehicle comes to a stop, the brake is released, or the wheel is no longer approaching
lockup. The EBCM also runs self diagnostics in order to check for any system malfunctions. Refer to Self-Diagnostics. If the EBCM detects a
malfunction with the system, the ECBM will illuminate the amber ABS indicator in order to alert the driver of a malfunction.
