Dodge 2000 DURANGO Service Manual page 194

5 - 40 BRAKES
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM . . . . . . . . . . . . . . . . 40
CONTROLLER ANTILOCK BRAKES . . . . . . . . . . . 41
HYDRAULIC CONTROL UNIT. . . . . . . . . . . . . . . . 41
WHEEL SPEED SENSOR. . . . . . . . . . . . . . . . . . . 42
ABS WARNING LAMP . . . . . . . . . . . . . . . . . . . . . 43
DIAGNOSIS AND TESTING
ANTILOCK BRAKES. . . . . . . . . . . . . . . . . . . . . . . 43
SERVICE PROCEDURES
BLEEDING ABS BRAKE SYSTEM . . . . . . . . . . . . 44
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM
DESCRIPTION
The antilock brake system (ABS) is an electroni-
cally operated, all wheel brake control system.
The system is designed to prevent wheel lockup
and maintain steering control during periods of high
wheel slip when braking. Preventing lockup is accom-
plished by modulating fluid pressure to the wheel
brake units.
The hydraulic system is a three channel design.
The front wheel brakes are controlled individually
and the rear wheel brakes in tandem (Fig. 1). The
ABS electrical system is separate from other electri-
cal circuits in the vehicle. A specially programmed
controller antilock brake unit operates the system
components.
ABS system major components include:
• Controller Antilock Brakes (CAB)
• Hydraulic Control Unit (HCU)
• Wheel Speed Sensors (WSS)
• ABS Warning Light
OPERATION
Battery voltage is supplied to the CAB ignition ter-
minal when the ignition switch is turned to Run posi-
tion. The CAB performs a system initialization
procedure at this point. Initialization consists of a
static and dynamic self check of system electrical
components.
The static and dynamic checks occurs at ignition
start up. During the dynamic check, the CAB briefly
cycles the pump and solenoids to verify operation. An
audible noise may be heard during this self check.
This noise should be considered normal.
FOUR WHEEL ANTILOCK BRAKES
TABLE OF CONTENTS
page
REMOVAL AND INSTALLATION
CONTROLLER ANTILOCK BRAKES . . . . . . . . . . . 44
ANTILOCK CONTROL ASSEMBLY . . . . . . . . . . . . 44
FRONT WHEEL SPEED SENSOR - 4x2 . . . . . . . . 45
FRONT WHEEL SPEED SENSOR - 4x4 . . . . . . . . 46
TONE WHEEL . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
REAR WHEEL SPEED SENSOR . . . . . . . . . . . . . 46
EXCITER RING . . . . . . . . . . . . . . . . . . . . . . . . . . 47
SPECIFICATIONS
TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . . 47
Fig. 1 Antilock Brake System
1 – MASTER CYLINDER AND RESERVOIR
2 – POWER BRAKE BOOSTER
3 – WIRES TO WHEEL SPEED SENSORS
4 – RIGHT REAR WHEEL
5 – LEFT REAR WHEEL
6 – HYDRAULIC BRAKE LINES TO WHEELS
7 – COMBINATION VALVE
8 – HARNESS
9 – RIGHT FRONT WHEEL
10 – LEFT FRONT WHEEL
11 – CAB/HCU
If an ABS component exhibits a fault during ini-
tialization, the CAB illuminates the amber warning
light and registers a fault code in the microprocessor
memory.
The CAB monitors wheel speed sensor inputs con-
tinuously while the vehicle is in motion. However,
the CAB will not activate any ABS components as
long as sensor inputs indicate normal braking.
DN
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