Dodge 2000 DURANGO Service Manual page 186

5 - 32 BRAKES
DESCRIPTION AND OPERATION
REAR WHEEL ANTILOCK . . . . . . . . . . . . . . . . . . 32
RWAL COMPONENT LOCATION . . . . . . . . . . . . . 33
CONTROLLER REAR WHEEL ANTILOCK
BRAKES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
RWAL VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
REAR WHEEL SPEED SENSOR AND
EXCITER RING . . . . . . . . . . . . . . . . . . . . . . . . . 34
BRAKE WARNING LAMPS . . . . . . . . . . . . . . . . . . 35
BRAKE LAMP SWITCH . . . . . . . . . . . . . . . . . . . . 36
DIAGNOSIS AND TESTING
REAR WHEEL ANTILOCK . . . . . . . . . . . . . . . . . . 36
DESCRIPTION AND OPERATION
REAR WHEEL ANTILOCK
DESCRIPTION
Rear Wheel Antilock (RWAL) brake system is stan-
dard equipment. The RWAL brake system is designed
to prevent rear wheel lock-up under heavy braking
conditions on virtually all types of road surfaces.
RWAL braking is desirable because a vehicle which is
stopped without locking the wheels will retain direc-
tional stability. This allows the driver to retain
greater control of the vehicle during braking.
The RWAL components include:
• RWAL Valve
• Controller Antilock brake (CAB)
• Rear Wheel Speed Sensor (WSS)
OPERATION
When the brakes are applied, hydraulic fluid is
routed from the master cylinder's secondary circuit,
through the combination valve, to the RWAL valve.
From there hydraulic fluid is routed to the rear
brake wheel cylinders. The Controller Antilock Brake
monitors rear wheel speed through the rear wheel
speed sensor. If a wheel is about to lock-up, the CAB
signals the RWAL valve. The RWAL valve modulates
the hydraulic brake pressure to the rear wheels to
prevent wheel lock-up.
REAR WHEEL ANTILOCK BRAKES
TABLE OF CONTENTS
page
RWAL SERVICE PRECAUTIONS . . . . . . . . . . . . . 36
SERVICE PROCEDURES
REAR WHEEL ANTILOCK BRAKE BLEEDING . . . 37
REMOVAL AND INSTALLATION
CONTROLLER . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
RWAL VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
REAR WHEEL SPEED SENSOR . . . . . . . . . . . . . 38
EXCITER RING . . . . . . . . . . . . . . . . . . . . . . . . . . 39
SPECIFICATIONS
TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . . 39
NORMAL BRAKING
During light brake application, rear wheel deceler-
ation is not sufficient to activate the antilock system
components. During a normal stop hydraulic brake
fluid flows unrestricted to the rear wheel cylinders to
stop the vehicle. The antilock solenoid valves are
inactive. The isolation valve is open and the dump
valve is closed allowing normal fluid flow to the rear
wheel cylinders.
REAR WHEEL ANTILOCK BRAKING
If the CAB senses impending rear wheel lock-up, it
will energize the isolation solenoid. This prevents a
further increase of driver induced brake pressure to
the rear wheels. If this initial action is not enough to
prevent rear wheel lock-up, the CAB will momen-
tarily energize a dump solenoid. This opens the
dump valve to vent a small amount of isolated rear
brake pressure to an accumulator. The action of fluid
moving to the accumulator reduces the isolated brake
pressure at the wheel cylinders. The dump (pressure
venting) cycle is limited to very short time periods
(milliseconds). The CAB will pulse the dump valve
until rear wheel deceleration reaches the desired slip
rate programmed into the CAB. The system will
switch to normal braking once wheel locking tenden-
cies are no longer present.
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