Subaru SVX 1992 Manual page 842

4-4 [IVI5A1]
BRAKES
5 . Anti-lock Brake System
A: OUTLINE
1. FEATURE
The ABS (Anti-lock brake system) electrically controls
brake fluid pressure to prevent wheel "lock" during
braking on slippery road surfaces, thereby improving
directional/steering stability as well as shortening the
braking distance .
If the ABS becomes inoperative, the fail-safe system
activates to ensure it acts as a conventional brake
system . The warning light also comes on to indicate that
the ABS is malfunctioning .
The front-and-rear wheels utilize a 4-sensor, 4-channel
control design : the front wheels have an independent
control design" and the rear wheels have a select low
control design*'.
*1 : A system which independently controls fluid pres-
sure to left and right front wheels .
*2: A system which provides the same fluid pressure
control for the two rear wheels if either wheel starts to
"lock ."
2. COMPONENTS
The ABS consists of four tone wheels 5t, four ABS
sensors ®, an electronic control unit 70, a hydraulic
control unit ©, and a warning light 9~ .
ABS component parts
Item Function
Attached to each wheel hub and
Tone wheel rotates at the same speed as the
hub .
ABS sensor
Emits a wheel speed signal dur-
ing tone wheel rotation .
Receives wheel-speed signals
from speed sensors and sends a
Electronic control unit control signal to hydraulic unit so
that fluid pressure is optimally
controlled.
Receives a control signal from
Hydraulic control unit
electronic control unit and con-
trols respective wheel cylinder
fluid pressure .
Warning light
Comes on when ABS becomes
inoperative .
0
5
V
I 4
__ II
2
3 i/ '
' ----
J ~/
5
9
1 Master cylinder
--------
2 Wheel cylinder
3 Proportioning valve
4 ABS sensor
5 Tone wheel
_2 6 Hydraulic unit
7 Electronic control unit
8 Brake switch
9 Warning light
10 Transmission control unit
4
4
C4-556
Fig. 20
12