Equus 3123 - GM Code Reader (1982 - 1995) - Manual (Page 26)

3
3-1 GM
3.1 ANTILOCK BRAKE SYSTEMS (ABS)
3.1.1 What is ABS?
The ABS system utilizes several mechanical, hydraulic, and
electric/electronic components to automatically control
hydraulic brake pressure to the rear, or front and rear wheels
(depending on the brake system) to prevent wheel lock-up
during hard braking.
3.1.2 What are the benefits of ABS?
By preventing wheel lock-up during hard braking, ABS helps
maintain vehicle directional stability, as well as driver control,
ensuring a safer and more controlled stop in the shortest
distance.
3.1.3 How does the ABS system work?
The ABS system utilizes a computer called an Electronic
Brake Control Module (EBCM). The system also employs
several sensors and switches which monitor and control wheel
speed and hydraulic brake pressure when hard braking is
applied. When the wheel speed sensor(s) detect a potential
lock-up condition, a signal is sent to the EBCM. The EBCM, in
turn, sends a signal to the hydraulic system to relieve brake
pressure at the affected wheels, preventing the lock-up
condition.
3.1.4 What is the purpose of the Code Reader?
Most ABS systems generate diagnostic service codes when a
fault in the system is detected. These service codes are stored
in the EBCM. The Code Reader allows you to access the
EBCM's memory and recalls the service codes. The EBCM
outputs the service codes through the "Anti-Lock" light on the
vehicle's instrument panel.
3.2 APPLICATIONS
GM vehicles use a variety of Anti-Lock Brake Systems. This
Code Reader may be used to retrieve ABS service codes from
the following vehicle models: