Chrysler 1998 Voyager Service Manual page 170

5 - 88 BRAKES
DESCRIPTION AND OPERATION (Continued)
Fig. 2 Teves Mark 20 ICU
The ICU is located on the driver's side of the vehi-
cle, and is mounted to the front suspension cradle
(Fig. 3). The ABS only ICU contains the following
components for controlling the brake system hydrau-
lic pressure during ABS braking: The CAB, eight
valve solenoids, (four inlet valves and four outlet
valves) fluid accumulators a pump, and an electric
motor. The ABS with traction control ICU con-
tains the following components for controlling the
brake system hydraulic pressure during ABS braking
and traction control operation: The CAB, four sole-
noid controlled inlet valves, four solenoid controlled
outlet valves, two hydraulic shuttle valves, two ASR
valves, fluid accumulators a pump and an electric
motor. Also attached to the hydraulic control unit are
the master cylinder primary and secondary brake
tubes and the brake tubes going to each wheel of the
vehicle. (Fig. 3).
CAUTION: No components of the ICU are service-
able. If any component that makes up the ICU is
diagnosed as not functioning properly it MUST be
replaced. The replaceable components of the ICU,
are the HCU and the CAB (Fig. 2) and (Fig. 3). The
mounting bracket is also replaceable as a separate
component of the ICU. The remaining components
of the ICU are not serviceable items. No attempt
should ever be made to remove or service any indi-
vidual components of the HCU. This is due to the
concern of contamination entering the HCU while
performing a service procedure. Also no attempt
should ever be made to remove or service any indi-
vidual components of the CAB.
CAUTION: At no time when servicing the ICU
should a 12 volt power source be applied to any
electrical connector of the HCU or the CAB.
Fig. 3 ICU Mounting Location
INLET VALVES AND SOLENOIDS
There are four inlet solenoids, one for each wheel.
In the released position they provide a fluid path
from the master cylinder to the wheel brakes of the
vehicle. When the ABS cycle has been completed the
inlet solenoids will return to their released (open)
position.
OUTLET VALVES AND SOLENOIDS
There are four outlet solenoids, one for each wheel.
In the released position they are closed to allow for
normal braking. In the actuated (open) position, they
provide a fluid path from the wheel brakes of the
vehicle to the hydraulic control unit HCU accumula-
tors and pump motor. The outlet solenoids are spring
loaded in the released (closed) position during normal
braking.
ASR VALVE (ABS WITH TRACTION CONTROL
ONLY)
On vehicles equipped with ABS having traction
control, there are two special ASR valves located in
the HCU portion of the ICU. The ASR valves are a
normally open type valve and are solenoid actuated.
The special ASR valves are used to isolate the rear
(non-driven) wheels of the vehicle from the hydraulic
pressure that the HCU pump motor is sending to the
front (driven) wheels, when the traction control sys-
tem is in operation. The rear brakes need to be iso-
lated from the master cylinder when traction control
is in operation so that the HCU can build the
required hydraulic pressure to the front brakes.
HCU BRAKE FLUID ACCUMULATORS AND NOISE
DAMPING CHAMBER
There are two brake fluid accumulators in the
HCU. There is one brake fluid accumlator for the pri-
mary and secondary hydraulic circuits. The brake
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