Jeep Wrangler TJ. Manual — part 255
CAUTION: Before moving vehicle, pump brake
pedal several times to ensure the vehicle has a firm
enough pedal to stop the vehicle.
NOTE: After parking brake lining replacement, it is
recommended that the parking brake system be
conditioned prior to use. This is done by making
one stop from 25 mph on dry pavement or concrete
using light to moderate force on the parking brake
hand lever.
(17) Road test the vehicle to ensure proper func-
tion of the vehicle’s brake system.
ADJUSTMENT - WITH ADJUSTING TOOL
Adjustment can be made with a standard brake
gauge or with adjusting tool. Adjustment is per-
formed with the complete brake assembly installed
on the backing plate.
(1) Be sure parking brake lever is fully released.
(2) Raise vehicle so rear wheels can be rotated
freely.
(3) Remove plug from each access hole in brake
support plates.
(4) Loosen parking brake cable adjustment nut
until there is slack in front cable.
(5) Insert adjusting tool through support plate
access hole and engage tool in teeth of adjusting
screw star wheel (Fig. 68).
(6) Rotate adjuster screw star wheel (move tool
handle upward) until slight drag can be felt when
wheel is rotated.
(7) Push and hold adjuster lever away from star
wheel with thin screwdriver.
(8) Back off adjuster screw star wheel until brake
drag is eliminated.
(9) Repeat adjustment at opposite wheel. Be sure
adjustment is equal at both wheels.
(10) Install support plate access hole plugs.
(11) Adjust parking brake cable and lower vehicle.
(12) Depress park brake lever and make sure park
brakes hold the vehicle staionary.
(13) Release park brake lever.
CABLES
REMOVAL
REMOVAL - DRUM BRAKES
(1) Raise vehicle and loosen equalizer nuts until
rear cables are slack.
(2) Disengage cable from equalizer and remove
cable.
(3) Remove cable bracket from upper suspension
arm (Fig. 69).
(4) Remove rear wheel and brake drum.
(5) Remove secondary brake shoe and disconnect
cable from lever on brake shoe.
(6) Compress cable retainer with worm drive hose
clamp (Fig. 70) and remove cable from backing plate.
Fig. 68 Brake Adjustment
1 - STAR WHEEL
2 - LEVER
3 - BRAKE SHOE WEB
4 - SCREWDRIVER
5 - ADJUSTING TOOL
6 - ADJUSTER SPRING
Fig. 69 Parking Brake Cable Bracket
1 - UPPER SUSPENSION ARM
2 - WIRING BRACKET
3 - PARKING BRAKE CABLE BRACKET
TJ
BRAKES - BASE
5 - 37
SHOES (Continued)
REMOVAL - DISC BRAKES
(1) Raise and support the vehicle.
(2) Lockout the parking brake cable.
(3) Loosen the brake cable at the equalizer and
adjuster nut.
(4) Remove the cable from the front cable.
(5) Remove the cable from the equalizer.
(6) Remove the cable from the frame bracket.
(7) Remove the cable from the axle bracket.
(8) Remove the brake cable from the brake lever.
(Fig. 71)
INSTALLATION
INSTALLATION - DRUM BRAKES
(1) Install new cable in backing plate. Be sure
cable retainer is seated.
(2) Attach cable to lever on brake shoe and install
brake shoe on backing plate.
(3) Adjust brake shoes to drum with brake gauge.
(4) Install brake drum and wheel.
(5) Install cable/bracket on upper suspension arm.
(6) Engage cable in equalizer and install equalizer
nuts.
(7) Adjust parking brakes.
INSTALLATION - DISC BRAKES
(1) Install the brake cable to the brake lever.
(2) Install the cable to the axle bracket (Fig. 72).
(3) Install the cable to the equalizer (Fig. 72).
(4) Install the cable to the front cable.
(5) Adjust the brake cable at the equalizer and
using the adjuster nut.
Fig. 70 Cable Retainer
1 - CABLE RETAINER
2 - REAR CABLE
3 - WORM DRIVE HOSE CLAMP
Fig. 71 CABLE REMOVAL/INSTALLATION
1 - SUPPORT PLAT
2 - PARK BRAKE CABLE
3 - EQUALIZER
Fig. 72 REAR CABLE CONNECTED
1 - BRAKE HOSE
2 - ACTUATOR LEVER
3 - PARK BRAKE CABLE
5 - 38
BRAKES - BASE
TJ
CABLES (Continued)
BRAKES - ABS
TABLE OF CONTENTS
page
page
BRAKES - ABS
. . . . . . . . . . . . . . . . . . . . . . . . . 39
. . . . . . . . . . . . . . . . . . . . . . . . . . . 39
DIAGNOSIS AND TESTING - ANTILOCK
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
STANDARD PROCEDURE - BLEEDING ABS
. . . . . . . . . . . . . . . . . . . . . . 40
. . . . . . . . . . . . . . . . . . . . . . 40
FRONT WHEEL SPEED SENSOR
. . . . . . . . . . . . . . . . . . . . . . . . . 41
. . . . . . . . . . . . . . . . . . . . . . . . . . . 41
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
. . . . . . . . . . . . . . . . . . . . . . . . . 41
G-SWITCH
. . . . . . . . . . . . . . . . . . . . . . . . . 42
. . . . . . . . . . . . . . . . . . . . . . . . . . . 42
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
. . . . . . . . . . . . . . . . . . . . . . . . . 42
REAR WHEEL SPEED SENSOR
. . . . . . . . . . . . . . . . . . . . . . . . . 42
. . . . . . . . . . . . . . . . . . . . . . . . . . . 42
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
. . . . . . . . . . . . . . . . . . . . . . . . . 43
HCU (HYDRAULIC CONTROL UNIT)
. . . . . . . . . . . . . . . . . . . . . . . . . 43
. . . . . . . . . . . . . . . . . . . . . . . . . . . 43
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
. . . . . . . . . . . . . . . . . . . . . . . . . 44
BRAKES - ABS
DESCRIPTION
The purpose of the antilock system is to prevent
wheel lockup during periods of high wheel slip. Pre-
venting lockup helps maintain vehicle braking action
and steering control.
The antilock CAB activates the system whenever
sensor signals indicate periods of high wheel slip.
High wheel slip can be described as the point where
wheel rotation begins approaching 20 to 30 percent of
actual vehicle speed during braking. Periods of high
wheel slip occur when brake stops involve high pedal
pressure and rate of vehicle deceleration.
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 check occurs after the ignition switch is
turned to Run position. The dynamic check occurs
when vehicle road speed reaches approximately 30
kph (18 mph). During the dynamic check, the CAB
briefly cycles the pump and solenoids to verify oper-
ation.
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.
OPERATION
During normal braking, the master cylinder, power
booster and wheel brake units all function as they
would in a vehicle without ABS. The HCU compo-
nents are not activated.
During antilock braking fluid pressure is modu-
lated according to wheel speed, degree of slip and
rate of deceleration. A sensor at each wheel converts
wheel speed into electrical signals. These signals are
transmitted to the CAB for processing and determi-
nation of wheel slip and deceleration rate.
The ABS system has three fluid pressure control
channels. The front brakes are controlled separately
and the rear brakes in tandem. A speed sensor input
signal indicating a high slip condition activates the
CAB antilock program. Two solenoid valves are used
in each antilock control channel. The valves are all
located within the HCU valve body and work in pairs
to either increase, hold, or decrease apply pressure as
needed in the individual control channels. The sole-
noid valves are not static during antilock braking.
They are cycled continuously to modulate pressure.
Solenoid cycle time in antilock mode can be mea-
sured in milliseconds.
DIAGNOSIS AND TESTING - ANTILOCK
BRAKES
The ABS brake system performs several self-tests
every time the ignition switch is turned on and the
vehicle is driven. The CAB monitors the systems
input and output circuits to verify the system is oper-
TJ
BRAKES - ABS
5 - 39
ating correctly. If the on board diagnostic system
senses that a circuit is malfunctioning the system
will set a trouble code in its memory.
NOTE: An audible noise may be heard during the
self-test. This noise should be considered normal.
NOTE: The MDS or DRB III scan tool is used to
diagnose the ABS system. For additional informa-
tion refer to the Antilock Brake section in Group
8W. For test procedures refer to the Chassis Diag-
nostic Manual.
STANDARD PROCEDURE - BLEEDING ABS
BRAKE SYSTEM
ABS system bleeding requires conventional bleed-
ing methods plus use of the DRB scan tool. The pro-
cedure involves performing a base brake bleeding,
followed by use of the scan tool to cycle and bleed the
HCU pump and solenoids. A second base brake bleed-
ing procedure is then required to remove any air
remaining in the system.
(1) Perform base brake bleeding. Refer to base
brake section for procedure.
(2) Connect scan tool to the Data Link Connector.
(3) Select ANTILOCK BRAKES, followed by MIS-
CELLANEOUS, then ABS BRAKES. Follow the
instructions displayed. When scan tool displays TEST
COMPLETE, disconnect scan tool and proceed.
(4) Perform base brake bleeding a second time.
Refer to base brake section for procedure.
(5) Top off master cylinder fluid level and verify
proper brake operation before moving vehicle.
SPECIFICATIONS
T0RQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION
N·m
Ft. Lbs.
In. Lbs.
G-Sensor
Sensor Bolt
4-5
—
35-45
G-Sensor
Bracket Bolt
8-13
—
75-115
Hydraulic Control Unit
Bracket to HCU Bolts
6.5
—
57
Hydraulic Control Unit
Body Bracket Bolts
16-24
—
142-212
Hydraulic Control Unit
HCU to Body Bracket
Bolts
9-13
—
80-115
Hydraulic Control Unit
Brake Lines
15-18
—
130-160
Controller Anitlock Brakes
Mounting Bolt
7-9
—
60-80
Wheel Speed Sensors
Front Mounting Bolt
4-6
—
34-50
Wheel Speed Sensors
Rear Mounting Bolt
12-14
—
106-124
5 - 40
BRAKES - ABS
TJ
BRAKES - ABS (Continued)
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст