Dodge Durango (DN). Manual — part 246

BASE BRAKES

Disc Brake Caliper

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sliding
Bore . . . . . . . . . . . . . . . . . . . . . . 70 mm (2.75 in.)

Disc Brake Rotor

Type . . . . . . . . . . . . . . . . . . . . . . . . . . Ventilated
Dimensions . . . . . . . 287 x 24 mm (11.3 x 0.9 in.)
Max. Runout . . . . . . . . . . . . . . 0.102 mm (0.004)
Max. Thickness Variation . . . . . . . . . . 0.013 mm

(0.0005 in.)

Min. Rotor Thickness . . . . . 22.6 mm (0.8898 in.)

Brake Drum

Dimensions . . . . . . . . 279 x 57 mm (11 x 2.25 in.)
Max. Runout . . . . . . . . . . . . . 0.20 mm (0.008 in.)
Max. Diameter Variation . . . 0.076 mm (0.003 in.)

Brake Booster

Type . . . . . . . . . . . . . . . . . . . Tandem Diaphragm

Master Cylinder

Bore . . . . . . . . . . . . . . . . . . . . . 29 mm (1.125 in.)

TORQUE CHART

DESCRIPTION

TORQUE

Brake Booster

Mounting Nuts . . . . . . . . . . 28 N·m (250 in. lbs.)

Master Cylinder

Mounting Nuts . . . . . . . . . . 18 N·m (160 in. lbs.)

Caliper

Mounting Pins . . . . . . . . . . . . 30 N·m (22 ft. lbs.)

Wheel Cylinder

Bolts . . . . . . . . . . . . . . . . . . . 20 N·m (15 ft. lbs.)

Combination Valve

Bolt (RWAL) . . . . . . . . . 20-27 N·m (15-20 ft. lbs.)
Bolt (ABS) . . . . . . . . . . . 10-13 N·m (7-10 ft. lbs.)

Support Plate

Mounting Bolts/Nuts . . . . . . . . 64 N·m (47 ft. lbs)

Brake Line Fittings

Master Cylinder . . . . . . . . . 19 N·m (170 in. lbs.)
Combination Valve . . . . . . . 19 N·m (170 in. lbs.)
Wheel Cylinder . . . . . . . . . . 16 N·m (145 in. lbs.)

Brake Hose

Front Fitting . . . . . . . . . . . . 16 N·m (145 in. lbs.)
Front Bolt . . . . . . . . . . . . . . 28 N·m (250 in. lbs.)
Rear Fitting . . . . . . . . . . . . 19 N·m (170 in. lbs.)

SPECIAL TOOLS

BASE BRAKES

Install Dust Boot 8248

Universal Handle C-4171

DN

BRAKES

5 - 31

SPECIFICATIONS (Continued)

REAR WHEEL ANTILOCK BRAKES

TABLE OF CONTENTS

page

page

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

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

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.

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.

5 - 32

BRAKES

DN

RWAL COMPONENT LOCATION

DESCRIPTION

COMPONENT

LOCATION

FUNCTION

RWAL CONTROLLER

Driver side inner fender on a
bracket.

Tests, monitors and controls the
rear brake system.

HYDRAULIC CONTROL UNIT/
RWAL VALVE

Driver side inner fender on a
bracket.

Modulates hydraulic pressure to
rear brakes during an RWAL stop.

REAR WHEEL SPEED SENSOR

Top of the rear axle housing.

Sends an AC voltage sinewave to
the CAB whose frequency is
proportional to vehicle speed.

EXCITER RING

Ring gear inside the differential
housing.

Used to pull the magnetic field
across the wheel speed sensor’s
windings.

RED BRAKE WARNING LAMP

Instrument cluster.

Indicator for park brake
engagement, hydraulic brake
malfunction, or RWAL malfunction.

AMBER ABS WARNING LAMP

Instrument cluster.

Indicator of an RWAL malfunction.

BRAKE WARNING LAMP DIODE

Instrument panel harness near the
parking brake switch.

Isolates the park brake switch circuit
from the CAB for proper red brake
warning lamp operation.

ISOLATION AND DUMP VALVE
FUSE

Inside the CAB.

Fail-safe device for unwanted
control of the isolation and dump
solenoid/valves

ISOLATION AND DUMP
SOLENOID/VALVES

Inside the HCU/RWAL valve.

Used to modulation hydraulic
pressure to the rear brakes during
an RWAL stop.

CONTROLLER REAR WHEEL ANTILOCK
BRAKES

DESCRIPTION

The Controller Antilock Brakes (CAB) is a micro-

processor which handles testing, monitoring and con-
trolling the ABS brake system operation (Fig. 1). The
CAB functions are:

• Perform self-test diagnostics.

• Monitor the RWAL brake system for proper oper-

ation.

• Control the RWAL valve solenoids.

NOTE: If the CAB needs to be replaced, the rear
axle type and tire revolutions per mile must be pro-
gramed into the new CAB. For axle type refer to
Group 3 Differential and Driveline. For tire revolu-
tions per mile refer to Group 22 Tire and Wheels. To
program the CAB refer to the Chassis Diagnostic
Manual.

Fig. 1 RWAL CAB

1 – RWAL CAB

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BRAKES

5 - 33

DESCRIPTION AND OPERATION (Continued)

OPERATION

SYSTEM SELF-TEST

When the ignition switch is turned-on the micro-

processor RAM and ROM are tested. If an error
occurs during the test, a DTC will be set into the
RAM memory. However it is possible the DTC will
not be stored in memory if the error has occurred in
the RAM module were the DTC’s are stored. Also it
is possible a DTC may not be stored if the error has
occurred in the ROM which signals the RAM to store
the DTC.

CAB INPUTS

The CAB continuously monitors the speed of the

differential ring gear by monitoring signals generated
by the rear wheel speed sensor. The CAB determines
a wheel locking tendency when it recognizes the ring
gear is decelerating too rapidly. The CAB monitors
the following inputs to determine when a wheel lock-
ing tendency may exists:

• Rear Wheel Speed Sensor

• Brake Lamp Switch

• Brake Warning Lamp Switch

• Reset Switch

• 4WD Switch (If equipped)

CAB OUTPUTS

The CAB controls the following outputs for antilock

braking and brake warning information:

• RWAL Valve

• ABS Warning Lamp

• Brake Warning Lamp

RWAL VALVE

DESCRIPTION

The valve is located on the drivers side inner

fender under the hood. The valve modulates hydrau-
lic pressure to the rear brakes during an RWAL stop.

OPERATION

If the CAB senses that rear wheel speed decelera-

tion is excessive, it will energize an isolation solenoid
by providing battery voltage to the 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 momentarily energize a dump solenoid (the CAB
energizes the dump solenoid by providing battery
voltage to the solenoid). This opens the dump valve
to vent a small amount of isolated rear brake pres-
sure 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 (millisec-

onds). The CAB will pulse the dump valve until rear
wheel deceleration matches the desired slip rate pro-
grammed into the CAB. The system will switch to
normal braking once wheel locking tendencies are no
longer present.

A predetermined maximum number of consecutive

dump cycles can be performed during any RWAL
stop. If excessive dump cycles occur, a DTC will be
set and stored in the CAB memory. If during a RWAL
stop, the driver releases the brake pedal, the reset
switch contacts will open. This signal to the CAB is
an indication that pressure has equalized across the
RWAL valve. The CAB will then reset the dump cycle
counter in anticipation of the next RWAL stop. Addi-
tionally, any fluid stored in the accumulator will
force its way past the dump valve, back into the
hydraulic circuit and return to the master cylinder.

A fuse internal to the CAB, provides a fail-safe

device which prevents unwanted control over the iso-
lation and dump solenoids. The fuse is in series with
the isolation and dump solenoids output circuits. If
the internal fuse is open, the CAB cannot provide
voltage to energize either solenoid and RWAL stops
are prevented. If the fuse is open, the braking system
will operate normally but without antilock control
over rear brake pressure.

REAR WHEEL SPEED SENSOR AND EXCITER
RING

DESCRIPTION

The rear Wheel Speed Sensor (WSS) is mounted in

the rear differential housing (Fig. 2).

The exciter ring is press fitted onto the differential

carrier next to the final drive ring gear (Fig. 3). For

Fig. 2 Rear Wheel Speed Sensor Location

1 – DIFFERENTIAL HOUSING
2 – WHEEL SPEED SENSOR

5 - 34

BRAKES

DN

DESCRIPTION AND OPERATION (Continued)