
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping, or groaning noises heard by the
driver. This is normal and is due to pressurized fluid
being transferred between the master cylinder and
the brakes. If ABS operation occurs during hard
braking, some pulsation may be felt in the vehicle
body due to fore-and-aft movement of the suspension
as brake pressures are modulated.
At the end of an ABS stop, ABS is turned off when
the vehicle is slowed to a speed of 3±4 mph. There
may be a slight brake pedal drop anytime that the
ABS is deactivated, such as at the end of the stop
when the vehicle speed is less than 3 mph or during
an ABS stop where ABS is no longer required. These
conditions exist when a vehicle is being stopped on a
road surface with patches of ice, loose gravel, or sand
on it. Also, stopping a vehicle on a bumpy road sur-
face activates ABS because of the wheel hop caused
by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, some wheel slip is desired in order to achieve
optimum braking performance. Wheel slip is defined
as follows: 0 percent slip means the wheel is rolling
freely and 100 percent slip means the wheel is fully
locked. During brake pressure modulation, wheel slip
is allowed to reach up to 25±30 percent. This means
that the wheel rolling velocity is 25±30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.
Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
black tire marks since the wheel never reaches a
fully locked condition. However, tire marks may be
noticeable as light patched marks.
START-UP CYCLE
When the ignition is turned on, a popping sound
and a slight brake pedal movement may be noticed.
The ABS warning lamp will also be on for up to 5
seconds after the ignition is turned on. When the
vehicle is first driven off, a humming may be heard
or felt by the driver at approximately 20±40 kph
(12±25 mph). All of these conditions are a normal
function of ABS as the system is performing a diag-
nosis check.
PREMATURE ABS CYCLING
Symptoms of premature ABS cycling include: click-
ing sounds from the solenoid valves; pump/motor
running; and pulsations in the brake pedal. Prema-ture ABS cycling can occur at any braking rate of the
vehicle and on any type of road surface. Neither the
red BRAKE warning lamp, nor the amber ABS warn-
ing lamp, illuminate and no fault codes are stored in
the CAB.
Premature ABS cycling is a condition that needs to
be correctly assessed when diagnosing problems with
the antilock brake system. It may be necessary to use
a DRB scan tool to detect and verify premature ABS
cycling.
Check the following common causes when diagnos-
ing premature ABS cycling: damaged tone wheels;
incorrect tone wheels; damaged steering knuckle
wheel speed sensor mounting bosses; loose wheel
speed sensor mounting bolts; excessive tone wheel
runout; or an excessively large tone wheel-to-wheel
speed sensor air gap. Give special attention to these
components when diagnosing a vehicle exhibiting
premature ABS cycling.
After diagnosing the defective component, repair or
replace it as required. When the component repair or
replacement is completed, test drive the vehicle to
verify that premature ABS cycling has been cor-
rected.
ANTILOCK BRAKE SYSTEM COMPONENTS
The following is a detailed description of the
antilock brake system components. For information
on servicing base brake system components used in
conjunction with these components, see the BASE
BRAKE SYSTEM found at the beginning of this ser-
vice manual group.
MASTER CYLINDER
A vehicle equipped with ABS uses a different mas-
ter cylinder than a vehicle that is not equipped with
ABS. Vehicles equipped with ABS use a center port
master cylinder with only two outlet ports (Fig. 1).
The brake tubes from the primary and secondary
outlet ports on the master cylinder go directly to the
integrated control unit (ICU).
The master cylinder mounts to the power brake
booster in the same manner a non-ABS master cylin-
der does.
INTEGRATED CONTROL UNIT (ICU)
The hydraulic control unit (HCU) and the control-
ler antilock brake (CAB) used with this antilock
brake system are combined (integrated) into one
unit, which is called the integrated control unit (ICU)
(Fig. 2). The ICU is located on the driver's side of the
vehicle, and is mounted to the left front frame rail
below the master cylinder (Fig. 1).
5 - 66 BRAKESPL
DESCRIPTION AND OPERATION (Continued)

AMBER ABS WARNING LAMP
The amber ABS warning lamp is located in the
instrument cluster. The purpose of the warning lamp
is discussed in detail below.
When the ignition key is turned to the ON posi-
tion, the amber ABS warning lamp is lit until the
CAB completes its self-tests and turns off the lamp
(approximately 4 seconds). The amber ABS warning
lamp will illuminate when the CAB detects a condi-
tion that results in the shutdown of ABS function.
The CAB sends a message to the mechanical instu-
ment cluster (MIC) instructing it to turn on the
amber ABS warning lamp.
Under most conditions, when the amber ABS warn-
ing lamp is on, only the ABS function of the brake
system is affected; The electronic brake distribution
(EBD), the base brake system and the ability to stop
the vehicle are not affected.
WHEEL SPEED SENSOR (WSS)
At each wheel of the vehicle there is one wheel
speed sensor (WSS) and one tone wheel (Fig. 3) (Fig.
4) (Fig. 5) (Fig. 6). Each front wheel speed sensor is
attached to a boss in the steering knuckle. The front
tone wheel is part of the driveshaft outboard con-
stant velocity joint. The rear wheel speed sensor is
mounted to the rear disc brake adapter. The rear
tone wheel is an integral part of the rear wheel hub
and bearing.
The wheel speed sensor operates on electronic
energy supplied by the CAB and outputs a square
wave signal whose current alternates between two
constant levels. Its frequency is proportional to the
speed of the tone wheel. The output is available as
long as the sensor is powered and its state (high or
low) corresponds to the presence or absence of tone
wheel teeth. The output signal is sent to the CAB. If
a wheel locking tendency is detected by the CAB, it
will then modulate hydraulic pressure via the HCU
to prevent the wheel(s) from locking.
Correct ABS operation is dependent on accurate
wheel speed signals. The vehicle's tires and wheels
all must be the same size and type to generate accu-
rate signals. Variations in tire and wheel size can
produce inaccurate wheel speed signals.
Improper speed sensor-to-tone wheel clearance can
cause erratic speed sensor signals. The speed sensor
air gap is not adjustable, but should be checked when
applicable. Wheel speed sensor-to-tone wheel clear-
ance specifications can be found in the SPECIFICA-
TIONS section within this section in this service
manual group.
ELECTRONIC BRAKE DISTRIBUTION
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking.The EBD is used in place of a rear proportioning
valve. The EBD system uses the ABS system to con-
trol the slip of the rear wheels in partial braking
range. The braking force of the rear wheels is con-
trolled electronically by using the inlet and outlet
valves located in the integrated control unit.
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
Fig. 3 Left Front Wheel Speed Sensor
1 ± LEFT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
Fig. 4 Right Front Wheel Speed Sensor
1 ± RIGHT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
PLBRAKES 5 - 69
DESCRIPTION AND OPERATION (Continued)

ABS ELECTRONIC DIAGNOSIS
The following information is presented to give the
technician a general background on the diagnostic
capabilities of the ABS system. Complete electronic
diagnosis of the ABS system used on this vehicle is
covered in the Chassis Diagnostic Procedures manual.
Electronic diagnosis of the ABS system used on
this vehicle is performed using the DRBIIItscan
tool. The vehicle's scan tool diagnostic connector is
located under the steering column lower cover, to the
left side of the steering column (Fig. 10).
ABS SELF-DIAGNOSIS
The ABS system is equipped with a self-diagnosis
capability, which may be used to assist in the isola-
tion of ABS faults. The features are described below.
START-UP CYCLE
The self-diagnosis ABS start-up cycle begins when
the ignition switch is turned to the ON position.
Electrical checks are completed on ABS components,
including the CAB, solenoid continuity, and the relay
system operation. During this check the amber ABS
warning lamp is turned on for approximately 5 sec-
onds and the brake pedal may emit a popping sound,
moving slightly when the solenoid valves are
checked.
DRIVE-OFF CYCLE
The first time the vehicle is set in motion after an
ignition off/on cycle, the drive-off cycle occurs. This
cycle is performed when the vehicle reaches a speed
of approximately 20 kph (12 mph.).²The pump/motor is briefly activated to verify
function. When the pump/motor is briefly activated, a
whirling or buzzing sound may be heard by the
driver. This sound is normal, indicating the pump/
motor is running.
²The wheel speed sensor output correct operating
range is verified.
ONGOING TESTS
While the system is operating, these tests are per-
formed on a continuous basis:
²solenoid continuity
²wheel speed sensor continuity
²wheel speed sensor output
DIAGNOSTIC TROUBLE CODES (DTC's)
Diagnostic trouble codes (DTC's) are kept in the
controller's memory until either erased by the techni-
cian using the DRB, or erased automatically after
3500 miles or 255 ignition key cycles, whichever
occurs first. DTC's are retained by the controller
even if the ignition is turned off or the battery is dis-
connected. More than one DTC can be stored at a
time. When accessed, the number of occurrences
(ignition key cycles) and the DTC that is stored are
displayed. Most functions of the CAB and the ABS
system can be accessed by the technician for testing
and diagnostic purposes using the DRB.
LATCHING VERSUS NON-LATCHING DIAGNOSTIC TROUBLE
CODES
Some DTC's detected by the CAB are ªlatchingº
codes. The DTC is latched and ABS braking is dis-
abled until the ignition switch is reset. Thus, ABS
braking is non-operational even if the original DTC
has disappeared. Other DTC's are non-latching. Any
warning lamps that are turned on are only turned on
as long as the DTC condition exists; as soon as the
condition goes away, the amber ABS warning lamp is
turned off, although, in most cases, a DTC is set.
INTERMITTENT DIAGNOSTIC TROUBLE CODES
As with virtually any electronic system, intermit-
tent electrical problems in the ABS system may be
difficult to accurately diagnose. Most intermittent
electrical problems are caused by faulty electrical
connections or wiring. A visual inspection should be
done before trying to diagnose or service the antilock
brake system; this will eliminate unnecessary diag-
nosis and testing time. Perform a visual inspection
for loose, disconnected, damaged, or misrouted wires
or connectors; include the following components and
areas of the vehicle in the inspection.
(1) Inspect fuses in the power distribution center
(PDC) and the wiring junction block. Verify that all
fuses are fully inserted into the PDC and wiring
Fig. 10 ABS System Diagnostic Connector Location
1 ± DRIVER AIRBAG MODULE
2 ± PASSENGER AIRBAG MODULE
3 ± DATA LINK CONNECTOR
PLBRAKES 5 - 75
DIAGNOSIS AND TESTING (Continued)

AUTOMATIC TRANSMISSION OIL COOLER
Oil coolers are internal oil to coolant type, mounted
in the radiator lower tank (Fig. 9). Rubber oil lines
feed the oil cooler and the automatic transmission.
Use only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended. Tighten Oil Cooler Hose Clamps
to 2 N´m (18 in. lbs.).
ACCESSORY DRIVE BELTS
The accessory drive consist of two Poly-V type
drive belts (Fig. 10). One belt drives the generator,
the other drives the power steering pump and air
conditioning compressor (if equipped). The power
steering/air conditioning belt is tensioned by an auto-
matically controlled belt tensioner. The generator
belt is manually tensioned using an adjusting bolt
and a locking nut.
ENGINE BLOCK HEATER
The heater is mounted in a core hole (in place of a
core hole plug) in the engine block, with the heating
element immersed in coolant (Fig. 11). The engine
block heater is available as an optional accessory.
The heater is operated by ordinary house current
(110 Volt A. C.) through a power cord and connector
behind the radiator grille.
When in operation, the engine block heater can
provide easier engine starting and faster warm-up,
when vehicle is operated in areas having extremely
low temperatures.CAUTION: The power cord must be secured in its
retainer clips, and not positioned so it could con-
tact linkages or exhaust manifolds and become
damaged.
Fig. 9 Automatic Transmission Oil Cooler
1 ± CLAMPS
2 ± HOSES
Fig. 10 Accessory Drive Belts
1 ± GENERATOR BELT
2 ± AUTOMATIC BELT TENSIONER
3 ± POWER STEERING PUMP/A/C COMPRESSOR BELT
Fig. 11 Engine Block Heater
1 ± CORE PLUG
2 ± BLOCK HEATER
3 ± POWER CORD
7 - 6 COOLING SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

ENGINE THERMOSTAT TESTING
The thermostat is operated by a wax filled con-
tainer (pellet) which is sealed. When heated coolant
reaches a predetermined temperature the wax pellet
expands enough to overcome the closing spring and
water pump pressure, which forces the valve to open.
Coolant leakage into the pellet will cause a thermo-
stat to fail open. Do not attempt to free up a thermo-
stat with a screwdriver.
The thermostat that opens too soon type failure
mode is included in the on-board diagnosis. Thecheck engine light will not be lit by an open too soon
condition. If it has failed open, a diagnostic trouble
code (DTC) will be set. Do not change a thermostat
for lack of heater performance or temperature gauge
position, unless a DTC is present. See Diagnosis for
other probable causes. Thermostat failing shut is the
normal long term mode of failure, and normally, only
on high mileage vehicles. The temperature gauge will
indicate this. Refer to Diagnosis in this section.
ACCESSORY DRIVE BELT DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
BELT SLIPPAGE 1. Belt slipping because of
insufficient tension.1. Retension generator belt.
Replace the power steering belt's
automatic belt tensioner.
2. Belt excessively glazed or
hardened from heat and excessive
slippage.2. Replace belt.
3. Incorrect belt. 3. Replace belt.
4. Driven component bearing
failure.4. Replace faulty component.
5. Belt or pulley subjected to
substance (belt dressing, oil,
ethylene glycol) that has reduced
friction.5. Replace belt and clean pulleys.
BELT NOISE (OBJECTIONABLE
SQUEAL, SQUEAK, OR RUMBLE)1. Belt slippage. 1. Retension generator belt, replace
belt, or automatic belt tensioner.
2. Foreign material imbedded in
belt.2. Replace belt.
3. Non-uniform belt. 3. Replace belt.
4. Misaligned pulley(s). 4. Align accessories.
5. Non-uniform groove or eccentric
pulley.5. Replace pulley(s).
6. Bearing noise. 6. Locate and repair.
BELT ROLLED OVER IN GROOVE
OR BELT JUMPS OFF1. Broken cord in belt. 1. Replace belt.
2. Belt tension too loose, or too
tight.2. Retension generator belt.
Replace the power steering belt's
automatic belt tensioner.
3. Misaligned pulleys. 3. Align accessories.
4. Non-uniform grooves or eccentric
pulley.4. Replace pulley(s).
5. Foreign object(s) in grooves. 5. Remove foreign objects in
groove.
7 - 14 COOLING SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

COOLING SYSTEMÐDRAINING
NOTE: Drain, flush, and fill the cooling system at
the mileage or time intervals specified in Group 0,
Lubrication and Maintenance. If the solution is dirty,
rusty, or contains a considerable amount of sedi-
ment; clean and flush with a reliable cooling system
cleaner. Care should be taken in disposing of the
used engine coolant from your vehicle. Check gov-
ernmental regulations for disposal of used engine
coolant.
Without removing radiator pressure cap and
with system not under pressure:
(1) Shut engine off and turn draincock counter-
clockwise to open (Fig. 18).
(2) The coolant reserve tank should empty first,
then remove the pressure cap. (if not, Refer to Test-
ing Cooling System for leaks).
COOLING SYSTEMÐREFILLING
First clean system to remove old glycol, see Cooling
System Cleaning.
Fill system with 50/50 glycol/water mix. Use anti-
freeze described in Coolant section.
Continue filling system until full, this provides bet-
ter heater performance.Be careful not to spill
coolant on drive belts or the generator.
Fill coolant reserve/recovery system to at least the
FULL HOT mark with 50/50 solution. It may be nec-
essary to add coolant to the reserve/recovery con-
tainer after three or four warm-up/cool down cycles
to maintain coolant level between the FULL HOT
and ADD marks; if any trapped air was removed
from the system.
REMOVAL AND INSTALLATION
WATER PUMP
REMOVAL
(1) Raise vehicle on a hoist. Remove right inner
splash shield.
(2) Remove accessory drive belts. Refer to proce-
dure in this section.
(3) Drain cooling system. Refer to Cooling System
Draining in this section.
(4) Remove power steering pump attaching bolts
and set pump and assembly aside. Power steering
lines do not need to be disconnected.
(5) Remove upper and lower torque isolator struts.
(6) Support engine from the bottom and remove
right engine mount attaching bolt.
(7) Remove right engine mount bracket.
(8) Remove timing belt and timing belt tensioner.
Refer to Group 9, Engine for procedures.
(9) Remove camshaft sprocket and rear timing belt
cover. Refer to Group 9, Engine for procedures.
(10) Remove water pump attaching screws to
engine and remove pump (Fig. 19).
INSTALLATION
(1) Apply MopartDielectric Grease to O-ring
before installation.
(2) Install new O-ring gasket in water pump body
O-ring groove (Fig. 20).
CAUTION: Make sure O-ring gasket is properly
seated in water pump groove before tightening
screws. An improperly located O-ring may cause
damage to the O-ring, resulting in a coolant leak.
(3) Assemble pump body to block and tighten
screws to 12 N´m (105 in. lbs.). Pressurize cooling
system to 15 psi with pressure tester and check
water pump shaft seal and O-ring for leaks.
Fig. 18 Cooling System Drain Cock Location
1 ± DRAIN COCKFig. 19 Water Pump
1 ± CYLINDER BLOCK
2 ± PUMP BODY
PLCOOLING SYSTEM 7 - 19
SERVICE PROCEDURES (Continued)

(2) Connect recovery hose to water outlet connec-
tor/thermostat housing (Fig. 29).
(3) Fill container to proper level. Refer to Cooling
System Refilling in this section.
ENGINE BLOCK HEATER
REMOVAL
(1) Drain coolant from radiator and cylinder block.
Refer to Cooling System Draining in this section for
procedure.
(2) Detach power cord plug from heater (Fig. 31).
(3) Loosen screw in center of heater. Remove
heater assembly (Fig. 31).
INSTALLATION
(1) Thoroughly clean core hole and heater seat.
(2) Insert heater assembly with element loop posi-
tionedupward (Fig. 31).
(3) With heater seated, tighten center screw
securely to assure a positive seal.
(4) Connect power cord to block heater (Fig. 31).
(5) Fill cooling system with coolant to the proper
level, vent air, and inspect for leaks.
ACCESSORY DRIVE BELTS
POWER STEERING PUMP AND AIR CONDITIONING
COMPRESSOR BELT
REMOVAL
(1) Using a 17 mm wrench, rotate belt tensioner
clockwise (Fig. 33) until belt can be removed from
power steering pump pulley. Gently, release spring
tension on tensioner.
(2) Remove belt (Fig. 34).
INSTALLATION
(1) Install belt (Fig. 34) over all pulleys except for
the power steering pump pulley.
(2) Using a 17 mm wrench, rotate belt tensioner
clockwise (Fig. 33) until belt can be installed onto
power steering pulley. Release spring tension onto
belt.
NOTE: When installing drive belt onto pulleys,
make sure that belt is properly routed and all
V-grooves make proper contact with pulley grooves.
(3) After belt is installed, inspect belt length indi-
cator marks (Fig. 35). The indicator mark should be
within the minimum belt length and maximum belt
length marks. On a new belt, the indicator mark
should align approximately with the nominal belt
length mark.
Fig. 31 Engine Block Heater
1 ± CORE PLUG
2 ± BLOCK HEATER
3 ± POWER CORD
Fig. 32 Accessory Drive Belts
1 ± GENERATOR BELT
2 ± AUTOMATIC BELT TENSIONER
3 ± POWER STEERING PUMP/A/C COMPRESSOR BELT
7 - 24 COOLING SYSTEMPL
REMOVAL AND INSTALLATION (Continued)

GENERATOR BELT
REMOVAL
(1) Remove power steering pump/air conditioning
compressor drive belt.
(2) Loosen pivot bolt, then locking nut and adjust-
ing bolt (Fig. 36).
(3) Remove generator belt.
NOTE: When installing drive belt onto pulleys,
make sure that belt is properly routed and all
V-grooves make proper contact with pulley grooves.
INSTALLATION
(1) Install belt and/or adjust belt tension by tight-
ening adjusting bolt. Adjust belt to specification
shown in Belt Tension Chart.
NOTE: Due to space limitations, the use of a belt
tension gauge is limited. Therefore, measure the
belt deflection at the center span of the generator
belt. Refer to Belt Tension Chart for specifications.
(2) Tighten pivot bolt to 54 N´m (40 ft. lbs.) and
locking nut to 54 N´m (40 ft. lbs.) (Fig. 36).
Fig. 33 Accessory BeltÐRemoving
1 ± 17mm WRENCH
Fig. 34 Power Steering/Air Conditioning Belt
1 ± BELT
2 ± P/S PULLEY
3 ± TENSIONER PULLEY
4 ± CRANKSHAFT PULLEY
5 ± BELT6 ± P/S PULLEY
7 ± TENSIONER PULLEY
8 ± A/C PULLEY
9 ± CRANKSHAFT PULLEY
PLCOOLING SYSTEM 7 - 25
REMOVAL AND INSTALLATION (Continued)