2000 DODGE NEON ESP

ABS BRAKING HYDRAULIC CIRCUIT, SOLENOID
VALVE, AND SHUTTLE VALVE FUNCTION (ABS
WITH TRACTION CONTROL)
The hydraulic diagram (Fig. 8) shows the vehicle in
the ABS braking mode. The diagram shows one
wheel is slipping because the driver is attempting to
stop the vehicle at a faster rate than is allowed by
the surface on which the tires are riding.
²The hydraulic shuttle valve closes upon brake
application so that the pump/motor cannot siphon
brake fluid from the master cylinder.²The normally open and normally closed valves
modulate (build/decay) the brake hydraulic pressure
as required.
²The pump/motor is switched on so that the
brake fluid from the low pressure accumulators is
returned to the master cylinder circuits.
²The brake fluid is routed to either the master
cylinder or the wheel brake depending on the posi-
tion of the normally open valve.
Fig. 8 ABS With Traction Control - ABS Braking Hydraulic Circuit
1 ± OUTLET VALVE
2 ± PUMP PISTON
3 ± PUMP MOTOR (ON)
4 ± SUCTION VALVE
5 ± LOW PRESSURE ACCUMULATOR
6 ± NORMALLY CLOSED VALVE (MODULATING)
7 ± TO RIGHT FRONT WHEEL
8 ± NORMALLY OPEN VALVE (MODULATING)9 ± NORMALLY OPEN ASR VALVE (OFF)
10 ± FROM MASTER CYLINDER
11 ± HYDRAULIC SHUTTLE VALVE
12 ± MASTER CYLINDER PRESSURE
13 ± CONTROLLED WHEEL PRESSURE
14 ± LOW PRESSURE ACCUMULATOR PRESSURE
15 ± PUMP INTERSTAGE PRESSURE
16 ± NOISE DAMPER CHAMBER
5 - 72 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

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)

NOTE: It is not necessary to bleed the entire
hydraulic system after replacing just the master cyl-
inder unless the brake system has been open to air
for an excessive amount of time or air is present in
the lines. Only the master cylinder must be bled
and filled.
REMOVAL AND INSTALLATION
SERVICE WARNINGS AND CAUTIONS
Review this entire section prior to performing any
mechanical work on a vehicle equipped with ABS.
This section contains information on precautions per-
taining to potential component damage, vehicle dam-
age and personal injury which could result when
servicing an ABS equipped vehicle.
CAUTION: Only the recommended jacking or hoist-
ing positions for this vehicle are to be used when-
ever it is necessary to lift a vehicle. Failure to raise
a vehicle from the recommended locations could
result in lifting a vehicle by the hydraulic control
unit mounting bracket. Lifting a vehicle by the
hydraulic control unit mounting bracket will result
in damage to the mounting bracket and the hydrau-
lic control unit.
CAUTION: An attempt to remove or disconnect cer-
tain system components may result in improper
system operation. Only those components with
approved removal and installation procedures in
this manual should be serviced.CAUTION: Brake fluid will damage painted sur-
faces. If brake fluid is spilled on any painted sur-
faces, wash off with water immediately.
CAUTION: When performing any service procedure
on a vehicle equipped with ABS do not apply a
12-volt power source to the ground circuit of the
pump motor in the HCU. Doing this will damage the
pump motor and will require replacement of the
entire HCU.
CAUTION: If welding work is to be performed on
the vehicle, using an electric arc welder, the CAB
connector should be disconnected during the weld-
ing operation.
CAUTION: The CAB 25-way connector should never
be connected or disconnected with the ignition
switch in the ON position.
Many components of the ABS System are not ser-
viceable and must be replaced as an assembly. Do not
disassemble any component which is not designed to
be serviced.
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) Disconnect the wiring harness connector from
the brake fluid level switch on the master cylinder
reservoir (Fig. 12).
Fig. 11 Bleeding Master Cylinder
1 ± WOODEN DOWEL
2 ± MASTER CYLINDER
5 - 78 BRAKESPL
SERVICE PROCEDURES (Continued)

(7) Disconnect the primary and secondary brake
tubes from the master cylinder (Fig. 15). Install
plugs in the master cylinder outlet ports.
(8) Disconnect the 25-way connector from the con-
troller antilock brake (CAB) mounted on the inte-
grated control unit (ICU) and move it out of the way.
The connector is disconnected by pulling outward on
the connector lock (Fig. 16). This will unlock and
raise the 25-way connector out of the socket on the
CAB.(9) Tag the brake tubes coming from the master
cylinder as primary and secondary (Fig. 15). This is
done to avoid mix-up once the tubes are removed
from the vehicle.
(10) Disconnect and remove the primary and sec-
ondary brake tubes coming from the master cylinder
at the ICU hydraulic control unit (HCU) (Fig. 15).
(11) Disconnect the brake tubes going to each indi-
vidual brake at the HCU (Fig. 15).
(12) Remove the 3 bolts attaching the ICU to its
mounting bracket (Fig. 17).
(13) Remove the ICU from the vehicle.
Fig. 13 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. 14 Battery Tray Mounting
1 ± BATTERY TRAY MOUNTING NUTS
2 ± BATTERY TRAY MOUNTING BOLTS
3 ± AIR CLEANER BOX POST
Fig. 15 Brake Tube Locations
1 ± PRIMARY BRAKE TUBE
2 ± SECONDARY BRAKE TUBE
3 ± BRAKE TUBES FROM MASTER CYLINDER
4 ± BRAKE TUBES TO BRAKES
Fig. 16 Connector Lock Pulled Outward
1 ± MASTER CYLINDER
2 ± 25±WAY CONNECTOR
3 ± CAB
4 ± CONNECTOR LOCK PULLED OUTWARD
5 ± ICU
5 - 80 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

(14) Refer to DISASSEMBLY AND ASSEMBLY in
this section of this group for the procedure on sepa-
rating and reattaching the CAB to the HCU.
INSTALLATION
(1) Install the ICU onto its mounting bracket.
(2) Install the 3 bolts attaching the ICU to the
mounting bracket (Fig. 17). Tighten the 3 mounting
bolts to a torque of 11 N´m (97 in. lbs.)
(3) Install the four brake tubes going to the brakes
into their respective outlet ports on the ICU HCU
(Fig. 15). Using a crow foot on a torque wrench,
tighten the four brake tube nuts to a torque of 17
N´m (145 in. lbs.).
NOTE: When installing the brake tubes from the
master cylinder on the HCU, the brake tube with the
small tube nut is to be installed in the forward-most
port on the HCU with the small end going toward
the master cylinder secondary port.
(4) Install the primary and secondary brake tubes
from the master cylinder onto the HCU (Fig. 15). Do
not completely tighten the primary and secondary
tubes at this time.
(5) Connect the primary and secondary brake
tubes to the master cylinder ports (Fig. 15).
(6) Using a crow foot on a torque wrench, tighten
the primary and secondary brake tube nuts at both
the master cylinder and HCU to a torque of 17 N´m
(145 in. lbs.).
CAUTION: Before installing the 25-way connector
in the CAB, be sure the seal is properly installed in
the connector.(7) Install the 25-way connector into the socket of
the CAB as follows:
²Position the 25-way connector in the socket of
the CAB and carefully push it down as far as possi-
ble (Fig. 16).
²When the connector is fully seated into the CAB
socket, push the connector lock inward. This pulls
the connector into the socket of the CAB and locks it
in the installed position.
(8) Position the battery tray back in place. Install
the two bolts, then the two nuts mounting the bat-
tery tray to its bracket (Fig. 14). Tighten the two
bolts and nuts to a torque of 15 N´m (135 in. lbs.).
(9) Reinstall the air cleaner box onto its grom-
meted alignment post (Fig. 14).
(10) 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.
(11) Install the battery and clamp it in place.
Tighten the hold-down clamp bolt to a torque of 12
N´m (105 in. lbs.).
(12) Connect the positive, then the negative
(ground) cable on the battery.
(13) Bleed the base and the ABS hydraulic sys-
tems. Refer to ANTILOCK BRAKE SYSTEM
BLEEDING in this section of this service manual
group.
(14) Fill the master cylinder to the proper fill
level.
(15) Road test the vehicle to ensure proper opera-
tion of the base and antilock brake systems.
WHEEL SPEED SENSOR (FRONT)
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(2) Disconnect the wheel speed sensor cable con-
nector from the wiring harness on the inside of the
frame rail above the front suspension crossmember
(Fig. 18). The connector has a locking tab which that
must be pulled back before the connector release
tang can be depressed, releasing the connection.
(3) Remove the speed sensor cable grommet from
the retaining bracket attached to the brake hose on
the outside of the frame rail.
(4) Remove the bolt mounting the wheel speed sen-
sor head to the steering knuckle (Fig. 19).
Fig. 17 ICU Mounting Bolts
1 ± ICU
2 ± ICU MOUNTING BOLTS
PLBRAKES 5 - 81
REMOVAL AND INSTALLATION (Continued)

CAUTION: When removing a wheel speed sensor
from the knuckle, do not use pliers on the sensor
head. This may damage the sensor head. If the sen-
sor has seized, use a hammer and a punch to tap
the edge of the sensor head ear, rocking the sensor
side-to-side until free.
(5) Carefully, remove the sensor head from the
steering knuckle.(6) Remove the screw securing the wheel speed
sensor to the rear of the strut (Fig. 20). Remove the
wheel speed sensor.
INSTALLATION
CAUTION: Failure to install speed sensor cables
properly may result in contact with moving parts or
an over extension of cables causing an open cir-
cuit. Be sure that cables are installed, routed, and
clipped properly.
(1) Attach the wheel speed sensor to the strut
using the its mounting screw (Fig. 20).
(2) Install the wheel speed sensor head in the
steering knuckle (Fig. 19). Install the mounting bolt.
Tighten the mounting bolt to a torque of 12 N´m (105
in. lbs.).
(3) From the sensor bracket on the strut, loop the
sensor cable upward, then downward at the outside
of the frame rail. Install the speed sensor cable grom-
met onto the retaining bracket attached to the brake
hose on the outside of the frame rail.
(4) Loop the wheel speed sensor cable around the
bottom of the frame rail and connect it to the wiring
harness connector on the inside of the frame rail
(Fig. 18). Remember to push in the locking tab on the
connector.
(5) Install the tire and wheel assembly.
(6) Lower the vehicle.
(7) Road test vehicle to ensure proper operation of
the base brakes and ABS.
Fig. 18 Wiring Harness Connector
1 ± RIGHT FRONT WHEEL SPEED SENSOR CONNECTOR
2 ± RIGHT FRONT DRIVESHAFT
3 ± ENGINE OIL FILTER
Fig. 19 Wheel Speed Sensor
1 ± RIGHT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
Fig. 20 Wheel Speed Sensor At Strut
1 ± ABS WHEEL SPEED SENSOR ROUTING BRACKET (IF
EQUIPPED)
2 ± GROUND STRAP
3 ± GROUND STRAP SCREW
4 ± ABS SENSOR BRACKET SCREW (IF EQUIPPED)
5 - 82 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

DISASSEMBLY AND ASSEMBLY
INTEGRATED CONTROL UNIT
REMOVAL
NOTE: To replace the hydraulic control unit (HCU)
or the controller antilock brake (CAB) on this vehi-
cle, the entire integrated control unit (ICU) needs to
be removed from the vehicle. The CAB can then be
separated from the HCU. Do not attempt to replace
the CAB with the ICU mounted in the vehicle.
(1) Remove the ICU from the vehicle. Refer INTE-
GRATED CONTROL UNIT in the REMOVAL AND
INSTALLATION section in this section of the service
manual.
(2) Disconnect the pump/motor wiring harness
(Fig. 23) from the CAB.
(3) Remove the 4 bolts (Fig. 24) attaching the CAB
to the HCU.
(4) Remove the CAB from the HCU (Fig. 25).
INSTALLATION
(1) Install the CAB (Fig. 25) on the HCU.(2) Install the 4 bolts mounting the CAB (Fig. 24)
to the HCU. Tighten the CAB mounting bolts to a
torque of 2 N´m (17 in. lbs.).
(3) Plug the pump/motor wiring harness into the
CAB (Fig. 23).
(4) Install the ICU in the vehicle.
(5) Bleed the base and ABS hydraulic systems.
Refer to ANTILOCK BRAKE SYSTEM BLEEDING
in this section of this service manual group.
(6) Road test the vehicle to ensure proper opera-
tion of the base brakes and ABS.
Fig. 23 Pump/Motor To CAB Wiring Harness
1 ± CAB
2 ± PUMP MOTOR WIRING HARNESS
3 ± PUMP MOTOR
4 ± HCU VALVE BLOCK
Fig. 24 CAB Attaching Bolts
1 ± MOUNTING BOLTS
2 ± CAB
3 ± HCU VALVE BLOCK
Fig. 25 Remove/Install CAB
1 ± CAB
2 ± HCU VALVES
3 ± HCU VALVE BLOCK
5 - 84 BRAKESPL