Subaru LEGACY 2002 Quick Reference Index page 380

ABS
1. Anti-lock Brake System (ABS)
A: FEATURE
! The 5.3i type ABS used in the Legacy has a hydraulic control unit, an ABS control module, a
valve relay and a motor relay integrated into a single unit (called "ABSCM & H/U") for circuit sim-
plicity and reduced weight.
! The ABS electrically controls the brake fluid pressure to each wheel to prevent the wheel from
locking during braking on slippery road surfaces, thereby enabling the driver to maintain the direc-
tional control.
! If the ABS becomes inoperative, a fail-safe system is activated to ensure same level of braking
performance as with a conventional brake system. In that case, the warning light comes on to in-
dicate that the ABS is malfunctioning.
! The ABS is a 4-sensor, 4-channel system; the front wheel system is an independent control de-
1
sign* , while the rear wheel system is a select-low control design*
*1: A system which controls the front wheel brakes individually.
*2: A system which applies the same fluid pressure to both the rear wheels if either wheel starts
to lock. The pressure is determined based on the lower of the frictional coefficients of both wheels.
(1) ABS control module and hydraulic
control unit (ABSCM & H/U)
(2) Proportioning valve
(3) Diagnosis connector
(4) Data link connector
(for SUBARU select monitor)
ANTI-LOCK BRAKE SYSTEM (ABS)
(5) G sensor
(6) ABS warning light
(7) Tone wheel
(8) ABS sensor
ABS-2
2
.
(9) Wheel cylinder
(10) Automatic transmission control
module
(11) Brake switch
(12) Master cylinder
B4H2196A