ignition DODGE NEON 2000 Service Repair Manual

GROUP TAB LOCATORINIntroductionINaIntroduction0Lubrication and Maintenance2Suspension3Differential and Driveline5Brakes6Clutch7Cooling8ABattery8BStarting8CCharging System8DIgnition System8EInstrument Panel and Systems8EaInstrument Panel and Systems8FAudio System8GHorns8HVehicle Speed Control System8JTurn Signal and Flashers8KWindshield Wipers and Washers8LLamps8LaLamps8MRestraint System8NElectrically Heated Systems8OPower Distribution Systems8PPower Door Locks8QImmobilizer System8SPower Windows8TPower Mirrors8TaPower Mirrors8UChime Warning/Reminder System8WWiring Diagrams - LHD and RHD9Engine11Exhaust System13Frame and Bumpers14Fuel System19Steering21Transaxle22Tires and Wheels23Body24Heating and Air Conditioning24aHeating and Air Conditioning25Emission Control Systems

30,000 Miles (48 000 km) or at 24 months
²Change the engine oil.
²Replace the engine oil filter.
²Lubricate the front suspension lower ball joint.
²Inspect the tie rod ends and boot seals.
²Adjust the drive belt tension.
²Replace the engine air cleaner element (fil-
ter).
²Replace the engine spark plugs
²Change the automatic transaxle fluid.
37,500 Miles (60 000 km) or at 30 months
²Change the engine oil.
²Replace the engine oil filter.
45,000 Miles (72 000 km) or at 36 months
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the front brake pads and rear brake lin-
ings.
²Adjust the drive belt tension.
²Flush and replace the engine coolant at 36
months, regardless of mileage.
52,500 Miles (84 000 km) or at 42 months
²Change the engine oil.
²Replace the engine oil filter.
²Flush and replace the engine coolant if not done
at 36 months.
60,000 Miles (96 000 km) or at 48 months
²Change the engine oil.
²Replace the engine oil filter.
²Check the PCV valve and replace, if neces-
sary. Not required if previously changed.*
²Lubricate the front suspension lower ball joints.
²Replace the drive belts.
²Replace the engine air cleaner element (fil-
ter).
²Replace the ignition cables.
²Replace the spark plugs.
²Change the automatic transaxle fluid.
67,500 Miles (108 000 km) or at 54 months
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the front brake pads and rear brake lin-
ings.
75,000 Miles (120 000 km) or at 60 months
²Change the engine oil.
²Replace the engine oil filter.
²Adjust the drive belt tension.
²Flush and replace engine coolant if has been
30,000 miles (48 000 km) or 24 months since last
change.
82,500 Miles (132 000 km) or at 66 months
²Change the engine oil.
²Replace the engine oil filter.
²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) or 24 months since last
change.
90,000 Miles (144 000 km) or at 72 months
²Change the engine oil.
²Replace the engine oil filter.
²Check the PCV valve and replace, if neces-
sary. Not required if previously changed.*
²Lubricate the front suspension lower ball joints.
²Inspect the front brake pads and rear brake lin-
ings.
²Adjust the drive belt tension.
²Replace the engine air cleaner element (fil-
ter).
²Replace the spark plugs.
²Inspect the serpentine drive belt, replace if nec-
essary. This maintenance is not required if the belt
was previously replaced.
²Change the automatic transaxle fluid.
97,500 Miles (156 000 km) or at 78 months
²Change the engine oil.
²Replace the engine oil filter.
105,000 Miles (168 000 km) or at 84 months
²Change the engine oil.
²Replace the engine oil filter.
²Replace the engine timing belt.
²Adjust the drive belt tension.
*This maintenance is recommended by Daimler-
Chrysler Corporation to the owner but is not
required to maintain the emissions warranty.
NOTE: Inspection and service should also be per-
formed anytime a malfunction is observed or sus-
pected. Retain all receipts.
SCHEDULE ± B
3,000 Miles (5 000 km)
²Change the engine oil.
6,000 Miles (10 000 km)
²Change the engine oil.
²Replace the engine oil filter.
9,000 Miles (14 000 km)
²Change the engine oil.
²Inspect the front brake pads and rear brake lin-
ings.
0 - 4 LUBRICATION AND MAINTENANCEPL
SPECIFICATIONS (Continued)

12,000 Miles (19 000 km)
²Change the engine oil.
²Replace the engine oil filter.
15,000 Miles (24 000 km)
²Change the engine oil.
²Adjust the drive belt tension.
²Inspect theengine air cleaner element (fil-
ter).Replace as necessary.*
²Change the automatic transaxle fluid/filter and
adjust the bands.
18,000 Miles (29 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the front brake pads and rear brake lin-
ings.
21,000 Miles (34 000 km)
²Change the engine oil.
24,000 Miles (38 000 km)
²Change the engine oil.
²Replace the engine oil filter.
27,000 Miles (43 000 km)
²Change the engine oil.
²Inspect the front brake pads and rear brake lin-
ings.
30,000 Miles (48 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect thePCV valveand replace as neces-
sary.*
²Lubricate the front suspension lower ball joints.
²Adjust the drive belt tension.
²Replace theengine air cleaner element (fil-
ter).
²Replace thespark plugs
²Change the automatic transaxle fluid/filter and
adjust bands.
33,000 Miles (53 000 km)
²Change the engine oil.
36,000 Miles (58 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the front brake pads and rear brake lin-
ings.
²Flush and replace the engine coolant.
39,000 Miles (62 000 km)
²Change the engine oil.
42,000 Miles (67 000 km)
²Change the engine oil.
²Replace the engine oil filter.
45,000 Miles (72 000 km)
²Change the engine oil.
²Inspect the front brake pads and rear brake lin-
ings.
²Inspect theengine air cleaner element (fil-
ter).Replace as necessary.*
²Adjust the drive belt tension.
²Change the automatic transaxle fluid/filter and
adjust bands.
48,000 Miles (77 000 km)
²Change the engine oil.
²Replace the engine oil filter.
51,000 Miles (82 000 km)
²Change the engine oil.
²Flush and replace the engine coolant.
54,000 Miles (86 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect the front brake pads and rear brake lin-
ings.
57,000 Miles (91 000 km)
²Change the engine oil.
60,000 Miles (96 000 km)
²Change the engine oil.
²Replace the engine oil filter.
²Inspect thePCV valveand replace if neces-
sary.*
²Lubricate the front suspension lower ball joints.
²Replace the drive belts.
²Replace theengine air cleaner element (fil-
ter).
²Replace theignition cables
²Replace thespark plugs
²Check and replace, if necessary, theengine tim-
ing belton 3.0 liter engines.
²Change the automatic transaxle fluid/filter and
adjust bands.
63,000 Miles (101 000 km)
²Change the engine oil.
²Inspect the front brake pads and rear brake lin-
ings.
66,000 Miles (106 000 km)
²Change the engine oil.
²Replace the engine oil filter.
PLLUBRICATION AND MAINTENANCE 0 - 5
SPECIFICATIONS (Continued)

JUMP STARTING, TOWING, AND HOISTING
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
JUMP STARTING PROCEDURE...............7
TOWING RECOMMENDATIONS...............7
HOISTING RECOMMENDATIONS.............7SERVICE PROCEDURES
JUMP STARTING PROCEDURE...............7
TOWING RECOMMENDATIONS...............8
HOISTING RECOMMENDATIONS.............9
DESCRIPTION AND OPERATION
JUMP STARTING PROCEDURE
Describes the procedure for starting a disable vehi-
cle.
TOWING RECOMMENDATIONS
Describes the recommended towing procedures.
HOISTING RECOMMENDATIONS
Describes the location of hoisting and jacking
points so that the vehicle can be lifted by a floor jack
or hoist.
SERVICE PROCEDURES
JUMP STARTING PROCEDURE
WARNING: REVIEW ALL SAFETY PRECAUTIONS
AND WARNINGS IN GROUP 8A, BATTERY/START-
ING/CHARGING SYSTEMS DIAGNOSTICS. DO NOT
JUMP START A FROZEN BATTERY, PERSONAL
INJURY CAN RESULT. DO NOT JUMP START WHEN
MAINTENANCE FREE BATTERY INDICATOR DOT IS
YELLOW OR BRIGHT COLOR. DO NOT JUMP
START A VEHICLE WHEN THE BATTERY FLUID IS
BELOW THE TOP OF LEAD PLATES. DO NOT
ALLOW JUMPER CABLE CLAMPS TO TOUCH
EACH OTHER WHEN CONNECTED TO A BOOSTER
SOURCE. DO NOT USE OPEN FLAME NEAR BAT-
TERY. REMOVE METALLIC JEWELRY WORN ON
HANDS OR WRISTS TO AVOID INJURY BY ACCI-
DENTAL ARCING OF BATTERY CURRENT. WHEN
USING A HIGH OUTPUT BOOSTING DEVICE, DO
NOT ALLOW BATTERY VOLTAGE TO EXCEED 16
VOLTS. REFER TO INSTRUCTIONS PROVIDED
WITH DEVICE BEING USED.
CAUTION: When using another vehicle as a
booster, do not allow vehicles to touch. Electrical
systems can be damaged on either vehicle.
TO JUMP START A DISABLED VEHICLE:
(1) Raise hood on disabled vehicle and visually
inspect engine compartment for:
²Battery cable clamp condition, clean if necessary.
²Frozen battery.
²Yellow or bright color test indicator, if equipped.
²Low battery fluid level.
²Generator drive belt condition and tension.
²Fuel fumes or leakage, correct if necessary.
CAUTION: If the cause of starting problem on dis-
abled vehicle is severe, damage to booster vehicle
charging system can result.
(2) When using another vehicle as a booster
source, park the booster vehicle within cable reach.
Turn off all accessories, set the parking brake, place
the automatic transmission in PARK or the manual
transmission in NEUTRAL and turn the ignition
OFF.
(3) On disabled vehicle, place gear selector in park
or neutral and set park brake. Turn off all accesso-
ries.
(4) Connect jumper cables to booster battery. RED
clamp to positive terminal (+). BLACK clamp to neg-
ative terminal (-). DO NOT allow clamps at opposite
end of cables to touch, electrical arc will result.
Review all warnings in this procedure.
(5) On disabled vehicle, connect RED jumper cable
clamp to positive (+) terminal. Connect BLACK
jumper cable clamp to engine ground as close to the
ground cable attaching point as possible (Fig. 1).
(6) Start the engine in the vehicle which has the
booster battery, let the engine idle a few minutes,
then start the engine in the vehicle with the dis-
charged battery.
CAUTION: Do not crank starter motor on disabled
vehicle for more than 15 seconds, starter will over-
heat and could fail.
(7) Allow battery in disabled vehicle to charge to
at least 12.4 volts (75% charge) before attempting to
start engine. If engine does not start within 15 sec-
PLLUBRICATION AND MAINTENANCE 0 - 7

RED BRAKE WARNING LAMP
The red BRAKE warning lamp is located in the
instrument panel cluster and illuminates when a low
brake fluid condition occurs or when the parking
brake lever is applied with the ignition key in the
ON position. In addition, the red BRAKE warning
lamp illuminates when the ignition switch is moved
from the OFF to the ON or CRANK position. This is
done to check the bulb's operation.
Problems with this system will generally be of the
type where the warning lamp fails to turn on when it
should, or remains on when it should not.
The red BRAKE warning lamp LED is supplied
with current anytime the ignition switch is ON. The
bulb is illuminated by completing the ground circuit
using any of the following components:
²the brake fluid level switch located in the mas-
ter cylinder reservoir
²the parking brake switch mounted on the park-
ing brake lever (Fig. 10)
²the ignition switch when the ignition switch is
first moved to the ON or CRANK position
²the mechanical instrument cluster (MIC) (with
ABS)
²the ABS electronic brake distribution (EBD)
The brake fluid level switch is located in the brake
fluid reservoir of the master cylinder assembly (Fig.
1). The purpose of the switch is to provide the driver
with an early warning that the brake fluid level inthe master cylinder reservoir has dropped below an
acceptable level.
As the fluid drops below the minimum level, the
fluid level switch closes and grounds the red BRAKE
warning lamp circuit. This turns on the red BRAKE
warning lamp. At this time, the master cylinder fluid
reservoir must be checked and filled to the full mark
with DOT 3 brake fluid. An abnormal loss of brake
fluid in the master cylinder fluid reservoir could be
caused by a leak in the hydraulic system. The entire
brake hydraulic system should be checked for evi-
dence of a leak.
The red BRAKE warning lamp can be turned on by
the MIC in the case where the ABS is experiencing a
problem where the amber ABS warning lamp needs
to be illuminated and cannot. The MIC will then illu-
minate the red BRAKE warning lamp.
BRAKE LAMP SWITCH
The brake lamp switch is located under the instru-
ment panel, at the brake pedal arm (Fig. 13). It con-
trols operation of the vehicle's stop lamps. Also, if the
vehicle is equipped with speed control, the brake
lamp switch will deactivate the speed control when
the brake pedal is depressed.
When the brake pedal is depressed, the brake lamp
switch contacts are closed, completing the circuit to
the stop lamps, thus illuminating the stop lamps and
the center-high-mounted stop lamp (CHMSL).
Fig. 12 Drum-In-Hat Brake Rotor
1 ± REAR BRAKING DISK ROTOR
2 ± HAT SECTION OF REAR BRAKING DISC (PARKING BRAKE
BRAKING SURFACE)
Fig. 13 Brake Lamp Switch
1 ± SWITCH
2 ± CLIP
3 ± BRAKE PEDAL
4 ± CONNECTOR
5 - 8 BRAKESPL
DESCRIPTION AND OPERATION (Continued)

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)

The ABS with traction control ICU consists of the
following components: the CAB, eight (build/decay)
solenoid valves (four inlet valves and four outlet
valves), two hydraulic shuttle valves, two traction
control valves, valve block, fluid accumulators, a
pump, and an electric pump/motor.
The replaceable components of the ICU are the
HCU and the CAB. No attempt should be made to
service any components found inside of the HCU or
CAB.
CONTROLLER ANTILOCK BRAKE (CAB)
The controller antilock brake (CAB) is a micropro-
cessor-based device which monitors the ABS system
during normal braking and controls it when the vehi-
cle is in an ABS stop. The CAB is mounted to the
bottom of the HCU (Fig. 2). The CAB uses a 25-way
electrical connector on the vehicle wiring harness.
The power source for the CAB is through the ignition
switch in the RUN or ON position. The CAB is on
the PCI bus.
The primary functions of the (CAB) are to:
(1) monitor the antilock brake system for proper
operation.
(2) detect wheel locking or wheel slipping tenden-
cies by monitoring the speed of all four wheels of the
vehicle.
(3) control fluid modulation to the wheel brakes
while the system is in an ABS mode or the traction
control system is activated.
(4) store diagnostic information.
(5) provide communication to the DRB scan tool
while in diagnostic mode.
The CAB constantly monitors the antilock brake
system for proper operation. If the CAB detects a
fault, it will send a message to the mechanical instu-
ment cluster (MIC) instructing it to turn on the
amber ABS warning lamp and disable the antilock
braking system. The normal base braking system will
remain operational.
The CAB continuously monitors the speed of each
wheel through the signals generated by the wheel
speed sensors to determine if any wheel is beginning
to lock. When a wheel locking tendency is detected,
the CAB commands the CAB command coils to actu-
ate. The CAB command coils then open and close the
valves in the HCU that modulate brake fluid pres-
sure in some or all of the hydraulic circuits. The CAB
continues to control pressure in individual hydraulic
circuits until a locking tendency is no longer present.
The CAB contains a self-diagnostic program that
monitors the antilock brake system for system faults.
When a fault is detected, the amber ABS warning
lamp is turned on and the fault diagnostic trouble
code (DTC) is then stored in a diagnostic program
memory. These DTC's will remain in the CAB mem-
ory even after the ignition has been turned off. The
DTC's can be read and cleared from the CAB mem-
ory by a technician using the DRB scan tool. If not
cleared with a DRB scan tool, the fault occurrence
and DTC will be automatically cleared from the CAB
memory after the identical fault has not been seen
during the next 3,500 miles of vehicle operation.
Fig. 1 Master Cylinder And ICU
1 ± PRIMARY BRAKE TUBE
2 ± MASTER CYLINDER
3 ± SECONDARY BRAKE TUBE
4 ± ABS ICU
Fig. 2 Integrated Control Unit (ICU)
1 ± HCU
2 ± PUMP/MOTOR
3 ± CAB
PLBRAKES 5 - 67
DESCRIPTION AND OPERATION (Continued)

CONTROLLER ANTILOCK BRAKE INPUTS
²wheel speed sensors (four)
²stop lamp switch
²ignition switch
²system relay voltage
²ground
²traction control lamp
²diagnostic communication (PCI)
CONTROLLER ANTILOCK BRAKE OUTPUTS
²amber ABS warning lamp actuation (through
MIC)
²red BRAKE warning lamp actuation (through
MIC)
²traction control lamp actuation (through MIC)
²diagnostic communication. (PCI)
HYDRAULIC CONTROL UNIT (HCU)
The hydraulic control unit (HCU) is mounted to
the CAB as part of the ICU (Fig. 2). The HCU con-
trols the flow of brake fluid to the brakes using a
series of valves and accumulators. A pump/motor is
mounted on the HCU to supply build pressure to the
brakes during an ABS stop.
VALVES AND SOLENOIDS
The valve block contains four inlet valves and four
outlet solenoid valves. The inlet valves are spring-
loaded in the open position and the outlet valves are
spring-loaded in the closed position during normal
braking. The fluid is allowed to flow from the master
cylinder to the wheel brakes.
During an ABS stop, these valves cycle to maintain
the proper slip ratio for each wheel. The inlet valve
closes preventing further pressure increase and the
outlet valve opens to provide a path from the wheel
brake to the HCU accumulators and pump/motor.
This releases (decays) pressure from the wheel brake,
thus releasing the wheel from excessive slippage.
Once the wheel is no longer slipping, the outlet valve
is closed and the inlet valve is opened to reapply
(build) pressure.
There are four other valves in the HCU. These four
remaining valves are used for traction control. Two
traction control (TC) valves, mounted in the HCU
valve block, are normally in the open position and
close only when the traction control is applied. There
are also two shuttle valves which control pressure
return to the master cylinder under ABS and traction
control conditions.
These TC valves are used to isolate the rear (non-
driving) wheels of the vehicle from the hydraulic
pressure that the HCU pump/motor is sending to the
front (driving) wheels when traction control is being
applied. The rear brakes need to be isolated from the
master cylinder when traction control is beingapplied so the rear wheels do not drag. For more
information on the TC and shuttle valves, see TRAC-
TION CONTROL SYSTEM in this section.
BRAKE FLUID ACCUMULATORS
There are two fluid accumulators in the HCU: one
for the primary hydraulic circuit, and one for the sec-
ondary hydraulic circuit. Each hydraulic circuit uses
a 3 cc accumulator.
The fluid accumulators temporarily store brake
fluid that is removed from the wheel brakes during
an ABS cycle. This stored fluid is used by the pump/
motor to provide build pressure for the brake hydrau-
lic system. When the antilock stop is complete, the
accumulators are drained by the pump/motor.
There are two noise dampening chambers in the
HCU on this vehicle equipped with traction control.
PUMP/MOTOR
There are two pump assemblies in the HCU: one
for the primary hydraulic circuit, and one for the sec-
ondary hydraulic circuit. Both pumps are driven by a
common electric motor (Fig. 2). This DC-type motor
is integral to the HCU and is controlled by the CAB.
The pump/motor provides the extra amount of
brake fluid needed during antilock braking. Brake
fluid is released to the accumulators when the outlet
valve is opened during an antilock stop. The pump
mechanism consists of two opposing pistons operated
by an eccentric camshaft. In operation, these pistons
are used to purge fluid from the accumulators back
into the master cylinder circuits. When the antilock
stop is complete, the pump/motor drains the accumu-
lators.
The pump motor is also used to build pressure
when the system goes into traction control mode. For
more information, refer to TRACTION CONTROL
SYSTEM in this section.
The CAB may turn on the pump/motor when an
antilock stop is detected. The pump/motor continues
to run during the antilock stop and is turned off after
the stop is complete. Under some conditions, the
pump/motor runs to drain the accumulators during
the next drive-off.
The pump/motor is not a serviceable item; if it
requires replacement, the HCU must be replaced.
ABS FUSES
The ABS fuse and the ABS pump/motor fuse are
located in the power distribution center (PDC). Refer
to the sticker on the inside of the PDC cover for the
location of these fuses. The PDC is located on the
driver's side of the engine compartment between the
back of the battery and the brake master cylinder.
The CAB fuse can be found in the fuse junction
block under the instrument panel.
5 - 68 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)

DIAGNOSIS AND TESTING
SERVICE WARNINGS AND CAUTIONS
The ABS uses an electronic control module, the
CAB. This module is designed to withstand normal
current draws associated with vehicle operation.
Care must be taken to avoid overloading the CAB
circuits.
CAUTION: In testing for open or short circuits, do
not ground or apply voltage to any of the circuits
unless instructed to do so for a diagnostic proce-
dure.
CAUTION: These circuits should only be tested
using a high impedance multi-meter or the DRB
scan tool as described in this section. Power
should never be removed or applied to any control
module with the ignition in the ON position. Before
removing or connecting battery cables, fuses, or
connectors, always turn the ignition to the OFF
position.
CAUTION: Use only factory wiring harnesses. Do
not cut or splice wiring to the brake circuits. The
addition of after-market electrical equipment (car
phone, radar detector, citizen band radio, trailer
lighting, trailer brakes, etc.) on a vehicle equipped
with antilock brakes may affect the function of the
antilock brake system.
ABS GENERAL DIAGNOSTICS INFORMATION
This section contains information necessary to
diagnose the antilock brake system. Specifically, this
section should be used to help diagnose conditions
which result in any of the following:
(1) amber ABS warning lamp turned on.
(2) brakes lock-up on hard application.
Diagnosis of base brake conditions that are obvi-
ously mechanical in nature should be directed to
BASE BRAKE SYSTEM at the beginning of this
group.
Many ABS conditions judged to be a problem by
the driver may be normal operating conditions. See
ABS OPERATION in the DESCRIPTION AND
OPERATION section of this group to become famil-
iarized with the normal characteristics of this
antilock brake system.
ABS WIRING DIAGRAM INFORMATION
During the diagnosis and testing of the antilock
brake system it may become necessary to reference
the wiring diagrams covering the antilock brake sys-
tem and its components. For wiring diagrams refer to
GROUP 8W of this service manual. It will provide
you with the wiring diagrams and the circuit descrip-
tion and operation information covering the antilock
brake system.
ABS VEHICLE TEST DRIVE
Most ABS complaints will require a test drive to
properly duplicate and diagnose the condition.
WARNING: CONDITIONS THAT RESULT IN TURN-
ING ON THE RED BRAKE WARNING LAMP MAY
INDICATE REDUCED BRAKING ABILITY.
Before test driving a brake complaint vehicle, note
whether the red BRAKE warning lamp, amber ABS
warning lamp, or both are turned on. If it is the red
BRAKE warning lamp, there is a brake hydraulic
problem that must be corrected before driving the
vehicle. Refer to the BASE BRAKE SYSTEM for
diagnosis of the red BRAKE warning lamp. If the red
brake warning lamp is illuminated, there is also a
possibility that there is an ABS problem and the
amber ABS warning lamp is not able to illuminate,
so the MIC turns on the red Brake warning lamp by
default.
If the amber ABS warning lamp is on, test drive
the vehicle as described below. While the amber ABS
warning lamp is on, the ABS is not functional. The
ability to stop the car using the base brake system
should not be affected.
If a functional problem of the ABS is determined
while test driving the vehicle, refer to the Chassis
Diagnostic Procedures manual.
(1) Turn the key to the OFF position and then
back to the ON position. Note whether the amber
ABS warning lamp continues to stay on. If it does,
refer to the diagnostic manual.
(2) If the amber ABS warning lamp goes out, shift
into gear and drive the car to a speed of 20 kph (12
mph) to complete the ABS start-up and drive-off
cycles (see ABS ELECTRONIC DIAGNOSIS). If at
this time the amber ABS warning lamp comes on,
refer to the diagnostic manual.
(3) If the amber ABS warning lamp remains out,
drive the vehicle a short distance. Accelerate the
vehicle to a speed of at least 40 mph. Bring the vehi-
cle to a complete stop, braking hard enough to cause
the ABS to cycle. Again accelerate the vehicle past 25
mph. Refer to the diagnostic manual for further test-
ing of the antilock brake system.
5 - 74 BRAKESPL