2000 DODGE NEON battery

(4) Gently pull back on the brake pedal until the
pedal stops moving. This will ratchet the switch
plunger backward to the correct adjustment position.
(5) Check the stop lamps to verify they are operat-
ing properly and not staying on when the pedal is in
the released position.
MASTER CYLINDER
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
CAUTION: The vacuum in the power brake booster
must be pumped down before removing the master
cylinder to prevent the booster from sucking in any
contamination. This can be done by pumping the
brake pedal while the engine is not running until a
firm brake pedal is achieved.
(1) With the engine not running, pump the brake
pedal 4-5 strokes until the pedal feel is firm.
(2) Disconnect the negative (ground) cable from
the battery and isolate the cable.
(3) Disconnect the positive cable from the battery,
then remove the battery from the battery tray. There
is one nut securing the clamp on the backside of the
battery holding it in place.
(4) Remove the vehicle wiring harness connector
from brake fluid level switch in master cylinder
brake fluid reservoir (Fig. 44).(5) Disconnect the two brake tubes from the mas-
ter cylinder, and two brake tubes from the propor-
tioning valves (Fig. 45). Install plugs at all of the
open brake tube outlets on the master cylinder.
(6) Clean the area around where the master cylin-
der attaches to the power brake booster using a suit-
able brake cleaner such as MopartBrake Parts
Cleaner or an equivalent.
(7) Remove the two nuts attaching the master cyl-
inder to the power brake booster.
(8) Slide the master cylinder straight out of the
power brake booster.
(9) To remove the proportioning valves, unthread
each from the master cylinder.
INSTALLATION
NOTE: The master cylinder must be bled before
installing it on the vehicle.
(1) If removed, install the proportioning valves in
their master cylinder ports. The valves are identical,
so they can be installed in either master cylinder
port going to the rear brakes. Make sure the O-rings
on the proportioning valves are new.
(2) Bleed the master cylinder before installing it
on the vehicle. Refer to MASTER CYLINDER
BLEEDING in SERVICE PROCEDURES within this
section of this service manual group.
(3) Wipe the face of the power brake booster clean
where the master cylinder seal comes in contact
when it's installed. Do not get any cleaner or debris
inside the booster.
Fig. 44 Master Cylinder
1 ± POWER BRAKE BOOSTER PARTS IDENTIFICATION TAG
2 ± POWER BRAKE BOOSTER
3 ± BRAKE FLUID PRESSURE SWITCH
4 ± MASTER CYLINDER
Fig. 45 Brake Tubes At Master Cylinder
1 ± RIGHT FRONT BRAKE TUBE
2 ± LEFT FRONT BRAKE TUBE
3 ± LEFT REAR BRAKE TUBE
4 ± REAR PROPORTIONING VALVES
5 ± RIGHT REAR BRAKE TUBE
5 - 28 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

(4) Position the master cylinder on the studs of the
power brake booster, aligning the push rod of the
power brake booster with master cylinder piston
push rod. Carefully push the master cylinder onto
the studs until it contacts the face of the booster.
(5) Install the two master cylinder mounting nuts
and tighten each to a torque of 28 N´m (250 in. lbs.).
(6) Connect the four brake tubes to the master cyl-
inder and proportioning valve ports (Fig. 45). Tighten
all tube nuts to a torque of 17 N´m (145 in. lbs.).
(7) Connect the brake fluid level switch wiring
connector.
(8) Install the battery and clamp it in place.
(9) Connect the positive, then the negative
(ground) cable on the battery.
(10) Fill the master cylinder to the proper level.
(11) Road test the vehicle to ensure proper opera-
tion of the brakes.
BRAKE FLUID RESERVOIR
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
NOTE: The master cylinder does not need to be
removed from the power brake booster for removal
and installation of the brake fluid reservoir.
REMOVAL
(1) Clean the master cylinder housing and brake
fluid reservoir exterior surfaces.
(2) Remove the brake fluid reservoir cap. Using a
clean syringe or siphoning tool, empty as much brake
fluid as possible from the reservoir.
(3) Remove the vehicle wiring harness connector
from brake fluid level switch in master cylinder
brake fluid reservoir (Fig. 44).
(4) Remove the two plastic pins holding the reser-
voir to the master cylinder (Fig. 46).
(5) Lift the reservoir from the master cylinder
casting.
(6) Remove the grommets sealing the reservoir to
the master cylinder housing (Fig. 47).
INSTALLATION
(1) Install new sealing grommets in the master
cylinder housing (Fig. 47).
(2) Lubricate the sealing grommets with fresh
clean DOT 3 brake fluid. Place the reservoir in posi-
tion over the grommets making sure the filler hole is
towards the front of the vehicle. Seat the reservoir
into the grommets. While holding the reservoir firmly
against the grommets, install the two plastic pins
previously removed through their mounting holes
until they protrude out the other side of the master
cylinder reservoir (Fig. 46).
(3) Connect the brake fluid level switch wiring
connector (Fig. 44).
Fig. 46 Master Cylinder Reservoir
1 ± BRAKE FLUID LEVEL SWITCH RETAINING TABS
2 ± RESERVOIR RETAINING PINS
3 ± SEAL
Fig. 47 Sealing Grommets
1 ± MASTER CYLINDER
2 ± GROMMETS
3 ± SEAL
PLBRAKES 5 - 29
REMOVAL AND INSTALLATION (Continued)

(4) Fill the reservoir with fresh clean DOT 3 brake
fluid. Refer to BRAKE FLUID LEVEL CHECKING
in the SERVICE PROCEDURES section in this sec-
tion of this service manual group.
BRAKE FLUID LEVEL SWITCH
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
(1) Remove the vehicle wiring harness connector
from brake fluid level switch in master cylinder
brake fluid reservoir (Fig. 44).
(2) Push together the retaining tabs holding the
brake fluid level switch in place in the brake fluid
reservoir (Fig. 46).
(3) Pull the brake fluid level switch out the other
side of the reservoir.
INSTALLATION
(1) Align the brake fluid level switch with its
mounting hole on the left side of the master cylinder
brake fluid reservoir. Push the switch into the fluid
reservoir until the switch retaining tabs are
expanded on the other side of the reservoir, locking it
in place (Fig. 46).
(2) Connect the brake fluid level switch wiring
connector (Fig. 44).
POWER BRAKE BOOSTER
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
(1) Disconnect negative (ground) cable from the
battery and isolate the cable.
(2) Disconnect the positive cable from the battery,
then remove the battery from the battery tray. There
is one nut securing the clamp on the backside of the
battery holding it in place.
(3) Remove the one nut and one bolt securing the
air cleaner box in place, then disconnect the wiring
harness connector at the air inlet sensor.
(4) Lift the air cleaner box upward enough to clear
its grommeted alignment post (Fig. 48), then move
the air cleaner box forward just enough to access the
battery tray mounting bolts.(5) Remove the 2 bolts, then the 2 nuts mounting
the battery tray to its bracket (Fig. 48). Remove the
battery tray.
CAUTION: The vacuum in the power brake booster
must be pumped down before removing the master
cylinder to prevent the booster from sucking in any
contamination. This can be done by pumping the
brake pedal 4-5 times while the engine is not run-
ning until a firm brake pedal is achieved.
(6) Remove the master cylinder. For the master
cylinder without ABS removal and installation proce-
dure, refer to MASTER CYLINDER in this section of
this service manual group. For the master cylinder
with ABS removal and installation procedure, refer
to MASTER CYLINDER in the ANTILOCK BRAKE
SYSTEM section of this service manual group.
(7) If the vehicle is equipped with ABS, remove the
integrated control unit (ICU). Refer to INTEGRATED
CONTROL UNIT in REMOVAL AND INSTALLA-
TION within the ANTILOCK BRAKE SYSTEM sec-
tion of this service manual group for the procedure.
(8) If the vehicle is equipped with ABS, remove the
three bolts securing the ICU mounting bracket to the
frame rail.
(9) Disconnect the vacuum hoses from the check
valve on the power brake booster (Fig. 49), but do not
remove the check valve from power brake booster.
(10) Locate the brake pedal-to-power brake booster
input rod attachment under the instrument panel.
Position a small screwdriver (Fig. 50) under the cen-
ter tang of the retaining clip. Rotate the screwdriver
enough to allow the retaining clip tang to pass over
the end of the brake pedal pin. Remove the clip.
Fig. 48 Battery Tray Mounting
1 ± BATTERY TRAY MOUNTING NUTS
2 ± BATTERY TRAY MOUNTING BOLTS
3 ± AIR CLEANER BOX POST
5 - 30 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

CAUTION: Use only a new brake booster input rod-
to-brake pedal retaining clip to ensure proper
retainment.
(4) Connect the power brake booster input rod-to-
brake pedal pin. Install a new retaining clip. Do not
use the old clip.
(5) Connect all previously removed vacuum hoses
to the vacuum check valve (Fig. 49).
(6) If the vehicle is equipped with ABS, install the
ICU mounting bracket on the frame rail using its
three bolts. Tighten the nuts to a torque of 23 N´m
(200 in. lbs.).
(7) If the vehicle is equipped with ABS, reinstall
the ICU. Refer to INTEGRATED CONTROL UNIT in
REMOVAL AND INSTALLATION within the
ANTILOCK BRAKE SYSTEM section of this service
manual group for the procedure.
(8) Install the master cylinder. For the master cyl-
inder without ABS removal and installation proce-
dure, refer to MASTER CYLINDER in this section of
this service manual group. For the master cylinder
with ABS removal and installation procedure, refer
to MASTER CYLINDER in the ANTILOCK BRAKE
SYSTEM section of this service manual group.
(9) Position the battery tray back in place. Install
the two bolts, then the two nuts mounting the bat-
tery tray to its bracket (Fig. 48). Tighten the two
bolts and nuts to a torque of 34 N´m (25 ft. lbs.).
(10) Reinstall the air cleaner box onto its grom-
meted alignment post (Fig. 48).
(11) Install the one nut and one bolt securing the
air cleaner box in place, then connect the wiring har-
ness connector at the air inlet sensor.
(12) Install the battery and clamp it in place.
(13) Connect the positive, then the negative
(ground) cable on the battery.
(14) Adjust the stop lamp switch as necessary.
Refer to STOP LAMP SWITCH in the ADJUST-
MENTS section of this group.
(15) Bleed the base brake system.
(16) Road test the vehicle to ensure proper opera-
tion of the brakes.
PROPORTIONING VALVE
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
(1) Using a brake pedal holder, depress the brake
pedal past its first one inch of travel and hold it in
this position (Fig. 53). This will isolate the master
cylinder from the brake hydraulic system and willnot allow the brake fluid to drain out of the master
cylinder reservoir.
(2) Disconnect the brake tube from the proportion-
ing valve requiring removal (Fig. 54).
(3) Unscrew the Proportioning valve from the mas-
ter cylinder.
Fig. 53 Brake Pedal Holder
1 ± CLUTCH PEDAL (IF EQUIPPED WITH MANUAL TRANSAXLE)
2 ± THROTTLE PEDAL
3 ± BRAKE PEDAL HOLDING TOOL
4 ± STEERING WHEEL
5 ± DRIVER'S SEAT
6 ± BRAKE PEDAL
Fig. 54 Proportioning Valves On Master Cylinder
1 ± RIGHT FRONT BRAKE TUBE
2 ± LEFT FRONT BRAKE TUBE
3 ± LEFT REAR BRAKE TUBE
4 ± REAR PROPORTIONING VALVES
5 ± RIGHT REAR BRAKE TUBE
5 - 32 BRAKESPL
REMOVAL AND INSTALLATION (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)

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

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)

junction block. A label on the underside of the PDC
cover identifies the locations of the ABS fuses.
(2) Inspect the 25-way electrical connector at the
CAB for damaged, spread, or backed-out wiring ter-
minals. Verify that the 25-way connector is fully
inserted in the socket of the CAB. Be sure that wires
are not stretched tight or pulled out of the connector.
(3) Verify that all the wheel speed sensor connec-
tions are secure.
(4) Look for poor mating of connector halves or ter-
minals not fully seated in the connector body.
(5)
Check for improperly formed or damaged termi-
nals. All connector terminals in a suspect circuit should
be carefully reformed to increase contact tension.
(6) Look for poor terminal-to-wire connections.
This requires removing the terminal from the connec-
tor body to inspect it.
(7) Verify pin presence in the connector assembly
(8) Check for proper ground connections. Check all
ground connections for signs of corrosion, loose fas-
teners, or other potential defects. Refer to the wiring
diagrams for ground locations.
(9) Look for problems with the main power sources
of the vehicle. Inspect the battery, generator, ignition
circuits and other related relays and fuses.
If a visual check does not find the cause of the
problem, operate the car in an attempt to duplicate
the condition and record any trouble codes.
Most failures of the ABS disable the ABS function
for the entire ignition cycle even if the fault clears
before key-off. There are some failure conditions,
however, that allow ABS operation to resume during
the ignition cycle in which the trouble occurred even
if the trouble conditions are no longer present.
The following trouble conditions may result in
intermittent illumination of the amber ABS warning
lamp.
²Low system voltage. If Low System Voltage is
detected by the CAB, the CAB will turn on the ABS
Warning Lamp until normal system voltage is
achieved. Once normal voltage is seen at the CAB,
normal operation resumes.
²High system voltage. If high system voltage is
detected by the CAB, the CAB will turn on the
Amber ABS Warning Lamp until normal system volt-
age is achieved. Once normal voltage is again
detected by the CAB, normal ABS operation resumes.
Additional possible causes that may result in the
illumination of the amber ABS warning lamp are as
follows:
²Any condition that interrupts electrical current
to the CAB may cause the amber ABS warning lamp
to turn on intermittently.
²If PCI communication between the body control-
ler and the CAB is interrupted, the body controller
can turn on the amber ABS warning lamp.
TONE WHEEL
Tone wheels can cause erratic wheel speed sensor
signals. Inspect tone wheels for the following possible
causes:
²missing, chipped, or broken teeth
²contact with the wheel speed sensor
²wheel speed sensor to tone wheel alignment
²wheel speed sensor to tone wheel clearance
²excessive tone wheel runout
²tone wheel loose on its mounting surface
If a front tone wheel is found to need replacement,
the drive shaft must be replaced. No attempt should
be made to replace just the tone wheel. Refer to the
DIFFERENTIAL AND DRIVELINE group in this
service manual for removal and installation.
If a rear tone wheel is found to need replacement,
the rear hub and bearing must be replaced. No
attempt should be made to replace just the tone
wheel. Refer to the SUSPENSION group in this ser-
vice manual for removal and installation.
If wheel speed sensor to tone wheel contact is evi-
dent, determine the cause and correct it before
replacing the wheel speed sensor or tone wheel.
Check the gap between the speed sensor head and
the tone wheel to ensure it is within specifications.
Refer to SPECIFICATIONS in this section of the ser-
vice manual for the minimum and maximum wheel
speed sensor to tone wheel clearance.
Excessive wheel speed sensor runout can cause
erratic wheel speed sensor signals. Refer to SPECI-
FICATIONS in this section of the service manual for
the maximum allowed tone wheel runout. If tone
wheel runout is excessive, determine if it is caused
by a defect in the driveshaft assembly or hub and
bearing. Replace as necessary.
Tone wheels are pressed onto their mounting sur-
faces and should not rotate independently from the
mounting surface. Replacement of the front drive-
shaft or rear hub and bearing is necessary.
BRAKE FLUID CONTAMINATION
Indications of fluid contamination are swollen or
deteriorated rubber parts. Swelling indicates the
presence of petroleum in the brake fluid.
To test for contamination, put a small amount of
drained brake fluid in clear glass jar. If the fluid sep-
arates into layers, there is mineral oil or other fluid
contamination of the brake fluid.
If the brake fluid is contaminated, drain and thor-
oughly flush the brake system. Replace all the rubber
parts or components containing rubber coming into
contact with the brake fluid including: the master
cylinder; proportioning valves; caliper seals; wheel
cylinder seals; ABS hydraulic control unit; and all
hydraulic fluid hoses.
5 - 76 BRAKESPL
DIAGNOSIS AND TESTING (Continued)