spare tire CHRYSLER VOYAGER 2001 Service Manual

²three power feeds: valves, pump and microproces-
sor
²brake switch
²traction control switch
The CAB outputs include the following:
²ABS warning indicator actuation
²12 volts power to wheel speed sensors
²eight valves
²ten valves with traction control
²diagnostic communication
²PCI bus communication
²traction control lamp illumination
3.3.3 HYDRAULIC CONTROL UNIT
The hydraulic control unit (HCU) contains the
valve block assembly, two accumulators, and pump/
motor assembly. The HCU is attached to the CAB.
Valve Block Assembly:The valve block assem-
bly contains valves with four inlet valves and four
outlet valves. The inlet valves are spring-loaded in
the open position and the outlet valves are spring
loaded in the closed position. During an antilock
stop, these valves are cycled to maintain the proper
slip ratio for each wheel. If a wheel detects slip, the
inlet valve is closed to prevent and further pressure
increase. Then the outlet valve is opened to release
the pressure to the accumulators until the wheel is
no longer slipping. Once the wheel is no longer
slipping, the outlet valve is closed and the inlet
valve is opened to reapply pressure. If the wheel is
decelerating within its predetermined limits (prop-
er slip ratio), the inlet valve will close to hold the
pressure constant. On vehicles which are equipped
with a traction control system, there are two addi-
tional valves that isolate the master cylinder and
rear wheels. During a traction control event the
brakes are applied to reduce wheel slippage.
Pump Motor Assembly:The pump motor as-
sembly provides the extra amount of fluid needed
during antilock braking. The pump is supplied fluid
that is released to the accumulators when the outlet
valve is opened during an antilock stop. The pump
is also used to drain the accumulator circuits after
the antilock stop is complete. The pump is operated
by an integral electric motor. This DC-type motor is
controlled by the CAB. The CAB may turn on the
pump motor when an antilock stop is detected. The
pump continues to run during the antilock stop and
is turned off after the stop is complete. Under some
conditions, the pump motor will run to drain the
accumulators during the next drive off. The CAB
monitors the pump motor operation internally.
Accumulators:The accumulators provide tem-
porary fluid storage during an antilock stop and are
drained by the pump motor.
3.3.4 SWITCHES/SENSORS
Master Cylinder:The master cylinder is a stan-
dard tandem compensating port design for ABS and
non ABS systems. Traction control vehicles use a
dual center port master cylinder. For proper trac-
tion control operation the standard master cylinder
must not be used.
A fluid level switch is located in the master
cylinder fluid reservoir. The switch closes when a
low fluid level is detected. The fluid level switch
turns on the brake warning indicator by grounding
the indicator circuit. This switch does not disable
the ABS system.
Wheel Speed Sensors and Tone Wheels:One
active wheel speed sensor (WSS) is located at each
wheel and sends a small signal to the control
module (CAB). This signal is generated when a
toothed sensor ring (tone wheel) passes by a station-
ary wheel speed sensor. The CAB converts the
signals into digital signals for each wheel.
Because of internal circuitry, correct wheel speed
sensor function cannot be determined by a continu-
ity or resistance check through the sensor.
The front wheel speed sensor is attached to a boss
in the steering knuckle. The tone wheel is an
integral part of the front axle shaft. The rear speed
sensor is mounted though the bearing cover and the
rear tone wheel is an integral part of the rear
bearing hub. The wheel speed sensor air gap is not
adjustable. Refer to the service manual for wheel
speed sensor air gap and resistance specifications.
The four wheel speed sensors are serviced indi-
vidually. The front tone wheels are serviced as an
assembly with the outer constant velocity (C.V.)
joint housing. The rear tone wheels are serviced as
an assembly.
Correct antilock system operation is dependent
on tone wheel speed signals from the wheel speed
sensors. The vehicle's wheels and tires should all be
the same size and type to generate accurate signals.
In addition, the tires should be inflated to the
recommended pressure for optimum system opera-
tion. Variation in wheel and tire size or significant
variations in inflation pressure can produce inaccu-
rate wheel speed signals; however, the system will
continue to function when using the mini-spare.
3.3.5 SYSTEM INITIALIZATION
System initialization starts when the key is
turned to ªrunº. At this point, the CAB performs a
complete self-check of all electrical components in
the antilock systems.
Between 8-17 km/h (5-10 mph), a dynamic test is
performed. This will momentarily cycle the inlet
and outlet valves, check wheel speed sensor cir-
cuitry, and run the pump motor at 25 km/h (15
mph). The CAB will try to test the pump motor. If
3
GENERAL INFORMATION

wheel weight. It will not properly fit the contour of
the wheel.
Always verify the Balance. When using off-vehicle
equipment, rotate assembly 180 degrees on balance
equipment to verify balance. Variation should not be
more than 0.125 (
1¤8) ounce. If variation is more than
0.125 ounce, balancing equipment could be malfunc-
tioning.
If difficult to balance, break down the wheel and
tire assembly and check for loose debris inside tire.
Prior to disassembly, mark (index) the tire at the
valve stem. Use this mark in order to remount the
tire in its original orientation with respect to the
wheel.
STANDARD PROCEDURE - TIRE AND WHEEL
MATCH MOUNTING
Wheels and tires are match mounted at the factory.
This means that the high spot of the tire is matched
to the low spot on the wheel rim. This technique is
used to reduce runout in the wheel and tire assem-
bly. The high spot on the tire is marked with a paint
mark or a bright colored adhesive label on the out-
board sidewall. The low spot on the wheel is identi-
fied with a label on the outside of the rim and a dot
or line in the drop well area of the rim (inside where
the tire mounts). If the outside label has been
removed, the tire will have to be removed to locate
the dot or line on the inside of the rim. The tire can
then be match mounted to the tire.
Information on match mounting the tire to the
wheel can be found in Tire and Wheel Runout/Match
Mounting, items (2) through (5), within Diagnosis
And Testing - Tire And Wheel Vibration. (Refer to 22
- TIRES/WHEELS - DIAGNOSIS AND TESTING)
STANDARD PROCEDURE - TIRE AND WHEEL
ROTATION
NON-DIRECTIONAL TREAD PATTERN TIRES
Tires on the front and rear axles operate at differ-
ent loads and perform different functions. For these
reasons, they wear at unequal rates, and tend to
develop irregular wear patterns. These effects can be
reduced by timely rotation of tires. The benefits of
rotation are especially worthwhile. Rotation will
increase tread life, help to maintain mud, snow, and
wet traction levels, and contribute to a smooth, quiet
ride.
The suggested rotation method is the forward-cross
tire rotation method (Fig. 11). This method takes
advantage of current tire industry practice which
allows rotation of radial-ply tires. Other rotation
methods may be used, but may not have all the ben-
efits of the recommended method.
NOTE: Only the 4 tire rotation method may be used
if the vehicle is equipped with a low mileage or tem-
porary spare tire.
DIRECTIONAL TREAD PATTERN TIRES
Some vehicles are fitted with special high-perfor-
mance tires having a directional tread pattern. These
tires are designed to improve traction on wet pave-
ment. To obtain the full benefits of this design, the
tires must be installed so that they rotate in the cor-
rect direction. This is indicated by arrows on the tire
sidewalls.
Fig. 10 Aluminum Wheel Weight
1 - TIRE
2 - WHEEL
3 - WHEEL WEIGHT
Fig. 11 Forward-Cross Tire Rotation Method
22 - 6 TIRES/WHEELSRS
TIRES/WHEELS (Continued)

Performance tires will have a speed rating letter
after the aspect ratio number. For example, the letter
ªSº indicates that the tire is speed rated up to 112
mph (180 km/h). The speed rating is not always
printed on the tire sidewall.
²Q -up to 100 mph (160 km/h)
²S -up to 112 mph (180 km/h)
²T -up to 118 mph (190 km/h)
²U -up to 124 mph (200 km/h)
²H -up to 130 mph (210 km/h)
²V -up to 149 mph (240 km/h)
²Z -more than 149 mph (240 km/h) (consult the
tire manufacturer for the specific speed rating)
An All Season type tire will have eitherM+S,M
& S or M-S (indicating mud and snow traction)
imprinted on the side wall.
TIRE CHAINS
Refer to the owners manual supplied with the vehi-
cle to determine whether the use of tire chains is per-
mitted on this vehicle.
DESCRIPTION - RADIAL-PLY TIRES
Radial-ply tires improve handling, tread life, ride
quality and decrease rolling resistance.
Radial-ply tires must always be used in sets of four
and under no circumstances should they be used on
the front only. It is recommended that tires from dif-
ferent manufacturers NOT be mixed. They may bemixed with a temporary spare tire when necessary. A
maximum speed of 80 km/h (50 mph) is recom-
mended while a temporary spare is in use.
Radial-ply tires have the same load-carrying capac-
ity as other types of tires of the same size. They also
use the same recommended inflation pressures.
DESCRIPTION - REPLACEMENT TIRES
WARNING: FAILURE TO EQUIP THE VEHICLE WITH
TIRES HAVING ADEQUATE SPEED CAPABILITY
CAN RESULT IN SUDDEN TIRE FAILURE.
It is recommended that tires equivalent to the orig-
inal equipment tires be used when replacement is
needed.
Failure to use equivalent replacement tires may
adversely affect the safety and handling of the vehicle.
The original equipment tires provide a proper com-
bination of many characteristics such as:
²Ride
²Noise
²Handling
²Durability
²Tread life
²Traction
²Rolling resistance
²Speed capability
The use of oversize tires may cause interference
with vehicle components. Under extremes of suspen-
sion and steering travel, interference with vehicle
components may cause tire damage.
DESCRIPTION - SPARE TIRE (TEMPORARY)
The temporary (convenience) spare tire is designed
for emergency use only. The original tire should be
repaired and reinstalled, or replaced with a new, at
the first opportunity.
The temporary (convenience) spare tire should be
inflated to the pressure listed on its sidewall. Do not
exceed speeds of 80 km/h (50 mph) when the tempo-
rary spare tire is in use on the vehicle. Refer to the
Owner's Manual for more details.
DIAGNOSIS AND TESTING - TIRE NOISE
Unusual tire noise can be associated with tire and
wheel vibration or irregular tire wear. For vibration,
(Refer to 22 - TIRES/WHEELS - DIAGNOSIS AND
TESTING). For irregular tire wear, (Refer to 22 - TIRES/
WHEELS/TIRES - DIAGNOSIS AND TESTING).
DIAGNOSIS AND TESTING - TIRE/VEHICLE
LEAD
Use the following Vehicle Lead Diagnosis And Cor-
rection Chart to diagnose and correct a vehicle lead
or drift problem.
Fig. 17 Tire Identification
RSTIRES/WHEELS22-9
TIRES (Continued)