2002 CHRYSLER VOYAGER rear light

²Wheel bearings
²Engine
²Transmission
²Exhaust
²Propeller shaft (vibration)
²Vehicle body (drumming)
Driveline module noises are normally divided into
two categories: gear noise or bearing noise. A thor-
ough and careful inspection should be completed to
determine the actual source of the noise before
replacing the driveline module.
The rubber mounting bushings help to dampen-out
driveline module noise when properly installed.
Inspect to confirm that no metal contact exists
between the driveline module case and the body. The
complete isolation of noise to one area requires
expertise and experience. Identifying certain types of
vehicle noise baffles even the most capable techni-
cians. Often such practices as:
²Increase tire inflation pressure to eliminate tire
noise.
²Listen for noise at varying speeds with different
driveline load conditions
²Swerving the vehicle from left to right to detect
wheel bearing noise.
All driveline module assemblies produce noise to a
certain extent. Slight carrier noise that is noticeable
only at certain speeds or isolated situations should be
considered normal. Carrier noise tends to peak at a
variety of vehicle speeds. Noise isNOT ALWAYSan
indication of a problem within the carrier.
TIRE NOISE
Tire noise is often mistaken for driveline module
noise. Tires that are unbalanced, worn unevenly or
are worn in a saw-tooth manner are usually noisy.
They often produce a noise that appears to originate
in the driveline module.
Tire noise changes with different road surfaces, but
driveline module noise does not. Inflate all four tires
with approximately 20 psi (138 kPa) more than the
recommended inflation pressure (for test purposes
only). This will alter noise caused by tires, but will
not affect noise caused by the differential. Rear axle
noise usually ceases when coasting at speeds less
than 30 mph (48 km/h); however, tire noise contin-
ues, but at a lower frequency, as the speed is
reduced.
After test has been completed lower tire pressure
back to recommended pressure.
GEAR NOISE (DRIVE PINION AND RING GEAR)
Abnormal gear noise is rare and is usually caused
by scoring on the ring gear and drive pinion. Scoring
is the result of insufficient or incorrect lubricant in
the carrier housing.Abnormal gear noise can be easily recognized. It
produces a cycling tone that will be very pronounced
within a given speed range. The noise can occur dur-
ing one or more of the following drive conditions:
²Drive
²Road load
²Float
²Coast
Abnormal gear noise usually tends to peak within
a narrow vehicle speed range or ranges. It is usually
more pronounced between 30 to 40 mph (48 to 64
km/h) and 50 to 60 mph (80 to 96 km/h). When objec-
tionable gear noise occurs, note the driving condi-
tions and the speed range.
BEARING NOISE (DRIVE PINION AND
DIFFERENTIAL)
Defective bearings produce a rough growl that is
constant in pitch and varies with the speed of vehi-
cle. Being aware of this will enable a technician to
separate bearing noise from gear noise.
Drive pinion bearing noise that results from defec-
tive or damaged bearings can usually be identified by
its constant, rough sound. Drive pinion front bearing
is usually more pronounced during a coast condition.
Drive pinion rear bearing noise is more pronounced
during a drive condition. The drive pinion bearings
are rotating at a higher rate of speed than either the
differential side bearings or the axle shaft bearing.
Differential side bearing noise will usually produce
a constant, rough sound. The sound is much lower in
frequency than the noise caused by drive pinion bear-
ings.
Bearing noise can best be detected by road testing
the vehicle on a smooth road (black top). However, it
is easy to mistake tire noise for bearing noise. If a
doubt exists, the tire treads should be examined for
irregularities that often causes a noise that resem-
bles bearing noise.
ENGINE AND TRANSMISSION NOISE
Sometimes noise that appears to be in the driv-
eline module assembly is actually caused by the
engine or the transmission. To identify the true
source of the noise, note the approximate vehicle
speed and/or RPM when the noise is most noticeable.
Stop the vehicle next to a flat brick or cement wall
(this will help reflect the sound). Place the transaxle
inNEUTRAL. Accelerate the engine slowly up
through the engine speed that matches the vehicle
speed noted when the noise occurred. If the same
noise is produced, it usually indicates that the noise
is being caused by the engine or transaxle.
3 - 26 REAR DRIVELINE MODULERS
REAR DRIVELINE MODULE (Continued)
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SUPPORT PLATE - DRUM BRAKE
REMOVAL.............................64
INSTALLATION.........................64
WHEEL CYLINDERS
REMOVAL.............................65
INSPECTION..........................65
INSTALLATION.........................65
PARKING BRAKE
DESCRIPTION
DESCRIPTION........................65
DESCRIPTION - EXPORT...............66
OPERATION...........................66
STANDARD PROCEDURE
STANDARD PROCEDURE - PARKING
BRAKE AUTOMATIC ADJUSTER TENSION
RELEASE...........................66
STANDARD PROCEDURE - PARKING
BRAKE AUTOMATIC ADJUSTER TENSION
RESET.............................67
CABLES - PARKING BRAKE
REMOVAL
REMOVAL - PARKING BRAKE CABLE
(FRONT)............................67
REMOVAL - PARKING BRAKE CABLE
(INTERMEDIATE)......................68
REMOVAL - PARKING BRAKE CABLE
(RIGHT REAR)........................69
REMOVAL - PARKING BRAKE CABLE (LEFT
REAR)..............................70INSTALLATION
INSTALLATION - PARKING BRAKE CABLE
(FRONT)............................71
INSTALLATION - PARKING BRAKE CABLE
(INTERMEDIATE)......................71
INSTALLATION - PARKING BRAKE CABLE
(RIGHT REAR)........................72
INSTALLATION - PARKING BRAKE CABLE
(LEFT REAR).........................72
ADJUSTMENTS
ADJUSTMENT - PARKING BRAKE CABLES . 72
CABLES - PARKING BRAKE (EXPORT)
REMOVAL - FRONT CABLE...............72
INSTALLATION - FRONT CABLE............72
LEVER - PARKING BRAKE
REMOVAL.............................72
INSTALLATION.........................73
LEVER - PARKING BRAKE (EXPORT)
REMOVAL - PARKING BRAKE LEVER AND
FRONT CABLE.......................74
INSTALLATION - PARKING BRAKE LEVER
AND FRONT CABLE...................75
SHOES - PARKING BRAKE
REMOVAL.............................75
INSTALLATION.........................81
ADJUSTMENTS
ADJUSTMENT - PARKING BRAKE SHOES . . 83
BRAKES - BASE
DESCRIPTION
DESCRIPTION - BASE BRAKES
The base brake system consists of the following
components:
²Brake pedal
²Power brake booster
²Master cylinder
²Brake tubes and hoses
²Proportioning valve (non-ABS vehicles only)
²Disc brakes
²Drum brakes
²Brake lamp switch
²Brake fluid level switch
²Parking brakes
Front disc brakes control the braking of the front
wheels; rear braking is controlled by rear drum
brakes or rear disc brakes depending on options.
The hydraulic brake system is diagonally split on
both the non-antilock braking systems and antilock
braking systems. That means the left front and right
rear brakes are on one hydraulic circuit and the right
front and left rear are on the other.For information on the brake lamp switch, (Refer
to 8 - ELECTRICAL/LAMPS/LIGHTING - EXTERI-
OR/BRAKE LAMP SWITCH - DESCRIPTION)
Vehicles equipped with the optional antilock brake
system (ABS) use a system designated Mark 20e. It
is available with or without traction control. This
system shares most base brake hardware used on
vehicles without ABS. ABS components are described
in detail in ANTILOCK BRAKE SYSTEM.
DESCRIPTION - BASE BRAKES (EXPORT)
Four-Wheel Disc Antilock Brakes are standard on
all models.
OPERATION - BASE BRAKES
When a vehicle needs to be stopped, the driver
applies the brake pedal. The brake pedal pushes the
input rod of the power brake booster into the booster.
The booster uses vacuum to ease pedal effort as force
is transferred through the booster to the master cyl-
inder. The booster's output rod pushes in the master
cylinder's primary and secondary pistons applying
hydraulic pressure through the chassis brake tubes
to the brakes at each tire and wheel assembly.
The parking brakes are foot-operated. When
applied, the parking brake lever pulls on cables that
actuate brake shoes at each rear wheel. These shoes
RSBRAKES - BASE5-3
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RED BRAKE WARNING INDICATOR LAMP
CONDITION POSSIBLE CAUSES CORRECTION
RED BRAKE WARNING
LAMP ON1. Parking brake lever not fully
released.1. Release parking brake lever.
2. Parking brake warning lamp
switch on parking brake lever.2. Inspect and replace switch as necessary.
3. Brake fluid level low in reservoir. 3. Fill reservoir. Check entire system for
leaks. Repair or replace as required.
4. Brake fluid level switch. 4. Disconnect switch wiring connector. If
lamp goes out, replace switch.
5. Mechanical instrument cluster
(MIC) problem.5. Refer to appropriate Diagnostic
information.
6. Amber ABS Warning Indicator
Lamp also illuminated.6. Refer to appropriate Diagnostic
information.
BRAKE NOISE
CONDITION POSSIBLE CAUSES CORRECTION
CLICK OR SQUAWK ON
PEDAL APPLICATION1. Brake lamp switch. 1. Replace switch.
2. Brake Transmission Shift Interlock
Linkage.2. Lubricate BTSI linkage.
3. Pedal pivot bushings 3. Lubricate pivot bushings. Replace if
necessary.
DISC BRAKE CHIRP 1. Excessive brake rotor runout. 1. Follow brake rotor diagnosis and testing.
Correct as necessary.
2. Lack of lubricant on brake caliper
slides.2. Lubricate brake caliper slides.
3. Caliper/shoes not fully seated. 3. Reseat caliper/shoes.
DISC BRAKE RATTLE OR
CLUNK1. Broken or missing anti-rattle
spring clips on shoes.1. Replace brake shoes.
2. Caliper guide pins/bolts loose. 2. Tighten guide pins/bolts.
DISC BRAKE SQUEAK AT
LOW SPEED (WHILE
APPLYING LIGHT BRAKE
PEDAL EFFORT)1. Brake shoe linings. 1. Replace brake shoes.
DRUM BRAKE CHIRP 1. Lack of lubricant on brake shoe
support plate where shoes ride.1. Lubricate shoe contact areas on brake
shoe support plates.
DRUM BRAKE CLUNK 1. Drum(s) have threaded machined
braking surface.1. Replace brake drums as necessary.
DRUM BRAKE HOWL OR
MOAN1. Lack of lubricant on brake shoe
support plate where shoes ride and
at the anchor.1. Lubricate shoe contact areas on brake
shoe support plates and at the anchor.
2. Rear brake shoes. 2. Replace rear brake shoes.
DRUM BRAKE SCRAPING
OR WHIRRING1. ABS wheel speed sensor or tone
wheel.1. Inspect, correct or replace faulty
component(s).
RSBRAKES - BASE5-5
BRAKES - BASE (Continued)
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CAUTION: When installing the tension clip on the
automatic adjuster, it must be located on only the
threaded area of the adjuster assembly (Fig. 32). If
it is located on a non-threaded area of the adjuster,
the function of the automatic adjuster will be
affected.
(7) Install the tension clip (Fig. 32) attaching the
upper return spring to the automatic adjuster assem-
bly.
(8) Install the brake shoe to brake shoe lower
return springs on the brake shoes (Fig. 30) and (Fig.
31).
(9) Install automatic adjustment lever on the lead-
ing brake shoe of the rear brake assembly (Fig. 29).
(10) Install the actuating spring on the automatic
adjustment lever and leading brake shoe assembly
(Fig. 28).
(11) Verify that the automatic adjuster lever has
positive contact with the star wheel on the automatic
adjuster assembly.
(12) When all components of both rear brake
assemblies are correctly and fully installed, remove
the locking pliers from the front park brake cable.
(13) Adjust brake shoes assemblies so as not to
interfere with brake drum installation.
(14) Install the rear brake drums on the hubs.
(15) Adjust rear brake shoes.
(16) Install the wheel and tire assembly.
(17) Tighten the wheel mounting stud nuts in
proper sequence until all nuts are torqued to half
specification. Then repeat the tightening sequence to
the full specified torque of 135 N´m (100 ft. lbs.).
(18) Lower the vehicle.
(19) Push the parking brake lever (pedal) to the
floor once and release pedal. This will automatically
remove the slack from and correctly adjust the park-
ing brake cables.
(20) Road test vehicle. The automatic adjuster will
continue the brake adjustment during the road test
of the vehicle.
ADJUSTMENTS
ADJUSTMENT - REAR DRUM BRAKE SHOES
NOTE: Normally, self-adjusting drum brakes do not
require manual brake shoe adjustment. Although, in
the event of a brake shoe replacement, it is advis-
able to make the initial adjustment manually to
speed up the adjusting time.
NOTE: Before raising the vehicle, verify the parking
brake lever is fully released.(1) Raise the vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
(2) Remove rubber plug from rear brake adjusting
hole in the rear brake support plate.
(3) Insert a thin screwdriver through the adjusting
hole in the support plate and against the star wheel
of the adjusting screw. Move handle of the tool
upward rotating the star wheel until a slight drag is
felt when tire and wheel assembly is rotated.
(4) Insert a second thin screwdriver or piece of
welding rod into brake adjusting hole and push the
adjusting lever out of engagement with the star
wheel.Care should be taken so as not to bend
adjusting lever or distort lever spring.
(5) While holding the adjusting lever out of
engagement, back off the star wheel just enough to
ensure a free wheel with no brake shoe drag.
(6) Repeat the above adjustment at the other rear
wheel.
(7) Install the adjusting hole rubber plugs back in
the rear brake support plates.
(8) Lower the vehicle.
DISC BRAKE CALIPER -
FRONT
REMOVAL
REMOVAL - FRONT DISC BRAKE CALIPER
(DISC/DISC BRAKES)
(1) Depress the brake pedal past its first inch of
travel and hold it in this position using a brake pedal
depressor (holding) tool. This is done to isolate the
master cylinder from the brake hydraulic system dis-
allowing the brake fluid to completely drain out of
the brake fluid reservoir.
(2) Raise the vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
(3) Remove front wheel and tire assembly.
(4) Remove the banjo bolt connecting the brake
hose to the brake caliper. There are two washers (one
on each side of the brake hose fitting) that will come
off with the banjo bolt. Discard these washers.
(5) Remove the 2 caliper guide pin bolts.
(6) Remove the brake caliper from the adapter.
REMOVAL - FRONT DISC BRAKE CALIPER
(DISC/DRUM BRAKES)
(1) Using a brake pedal holding tool, depress the
brake pedal past its first one inch of travel and hold
it in this position. This will isolate the master cylin-
der from the brake hydraulic system and will not
5 - 26 BRAKES - BASERS
BRAKE PADS/SHOES - REAR DRUM (Continued)
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DISASSEMBLY - CALIPER PISTON AND SEAL
WARNING: UNDER NO CONDITION SHOULD HIGH
PRESSURE AIR EVER BE USED TO REMOVE A PIS-
TON FROM A CALIPER BORE. PERSONAL INJURY
COULD RESULT FROM SUCH A PRACTICE.NOTE: Before disassembling the brake caliper,
clean and inspect it. Refer to CLEANING AND
INSPECTION in this section.
NOTE: The safest way to remove the piston from
the caliper bore is to use the hydraulic pressure of
the vehicle's brake system.
(1) Following the removal procedure in DISC
BRAKE SHOES found in this section, remove the
caliper from the brake rotor and hang the assembly
on a wire hook away from rotor and body of the vehi-
cle so brake fluid cannot get on these components.
Remove the brake shoes, and place a small piece of
wood between the piston and caliper fingers.
(2) Carefully depress the brake pedal to hydrauli-
cally push piston out of its bore. Once completed,
apply and hold down the brake pedal to any position
beyond the first inch of pedal travel using a brake
pedal holding tool. This will prevent the fluid in the
master cylinder reservoir from completely draining
out.
(3) Disconnect the brake fluid flex hose from the
caliper assembly and remove it from the vehicle.
CAUTION: Do not use excessive force when clamp-
ing caliper in vise. Excessive vise pressure will
cause bore distortion.
(4) Mount the caliper in a vise equipped with pro-
tective jaws.
(5) Remove the piston dust boot from the caliper
and discard.
NOTE: Do not use a screw driver or other metal tool
for seal removal. Using such tools can scratch the
bore or leave burrs on the seal groove edges.
(6) Using a soft tool such as a plastic trim stick,
work the piston seal out of its groove in caliper pis-
ton bore (Fig. 47). Discard the old seal.
(7) Clean the piston bore and drilled passage ways
using alcohol or a suitable solvent. Wipe it dry using
only a lint-free cloth.
(8) Inspect the piston bore for scoring or pitting.
Bores that show light scratches or corrosion can usu-
ally be cleared of the light scratches or corrosion
using crocus cloth.
Fig. 45 Caliper Guide Pin Bolts
1 - DISC BRAKE CALIPER
2 - ADAPTER
3 - AXLE
4 - GUIDE PIN BOLTS
5 - DRIVESHAFT (AWD MODELS ONLY)
Fig. 46 Removing/Installing Caliper
1 - LIFT THIS END OF CALIPER AWAY FROM ADAPTER FIRST
2 - DISC BRAKE CALIPER
3 - ADAPTER ABUTMENT
4 - OUTBOARD BRAKE SHOE HOLD DOWN CLIP
5 - OUTBOARD BRAKE SHOE
6 - ROTOR
7 - ADAPTER
RSBRAKES - BASE5-31
DISC BRAKE CALIPER - REAR (Continued)
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(3) Using lubriplate, or equivalent, coat the sur-
face of the brake pedal pin where it contacts the
booster input rod.
CAUTION: When installing the brake pedal pin on
the power brake booster input rod, do not re-use
the old retaining clip.
(4) Install booster input rod on brake pedal pin
and install a NEW retaining clip (Fig. 87).
CAUTION: Do not reuse the original brake lamp
switch. The switch can only be adjusted once. That
is during initial installation of the switch. If the
switch is not adjusted properly or has beenremoved for some service, a new switch must be
installed and adjusted.
(5) Remove and replace the brake lamp switch
with a NEW switch. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - EXTERIOR/BRAKE LAMP
SWITCH - REMOVAL), (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - EXTERIOR/BRAKE LAMP
SWITCH - INSTALLATION)
(6) Install the silencer panel below the steering
column.
(7) Connect vacuum hose to check valve on power
brake booster.
CAUTION: The master cylinder (and its rear seal) is
used to create the seal for holding vacuum in the
vacuum booster. The vacuum seal on the master
cylinder MUST be replaced with a NEW seal when-
ever the master cylinder is removed from the vac-
uum booster.
CAUTION: When removing the vacuum seal from
the master cylinder do not use a sharp tool.
(8) Using a soft tool such as a trim stick, remove
the vacuum seal from the master cylinder mounting
flange.
(9) Install a NEW vacuum seal on rear mounting
flange of the master cylinder (Fig. 88).
(10) Position master cylinder on studs of booster,
aligning push rod on booster with master cylinder
piston.
(11) Install the two nuts mounting the master cyl-
inder to the booster (Fig. 78). Tighten both mounting
nuts to a torque of 25 N´m (225 in. lbs.).
Fig. 86 RHD Booster Removal/Installation
1 - POWER BRAKE BOOSTER
2 - MASTER CYLINDER
Fig. 87 Retaining Pin Installed On Brake Pedal Pin
1 - BRAKE PEDAL
2 - RETAINING CLIP
3 - BOOSTER INPUT ROD
Fig. 88 Vacuum Seal (Typical)
1 - MASTER CYLINDER ASSEMBLY
2 - VACUUM SEAL
5 - 54 BRAKES - BASERS
POWER BRAKE BOOSTER (Continued)
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the mounting nuts to a torque of 14 N´m (124 in.
lbs.).
(14) Install the battery tray. Install the two nuts
and one bolt attaching the battery tray to the vehicle.
Tighten the bolt and nuts to a torque of 14 N´m (124
in. lbs.).
(15) If vehicle is equipped with speed control, con-
nect the servo vacuum hose to the vacuum tank on
the battery tray.
(16) Install the battery, clamp and mounting nut.
(17) Install the positive battery cable on the bat-
tery.
(18) Install the negative battery cable on the bat-
tery.
(19) Install the battery thermal guard shield.
CAUTION: Do not reuse the original brake lamp
switch. The switch can only be adjusted once. That
is during initial installation of the switch. If the
switch is not adjusted properly or has been
removed for some service, a new switch must be
installed and adjusted.
(20) Remove and replace the brake lamp switch
with a NEW switch. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - EXTERIOR/BRAKE LAMP
SWITCH - REMOVAL), (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - EXTERIOR/BRAKE LAMP
SWITCH - INSTALLATION)
(21) Bleed the base brakes as necessary. (Refer to
5 - BRAKES - STANDARD PROCEDURE)
(22) Road test vehicle to ensure proper operation
of the brakes.
PROPORTIONING VALVE
DESCRIPTION - PROPORTIONING VALVE
(HEIGHT SENSING)
NOTE: Only vehicles without antilock brakes (ABS)
have a proportioning valve. Vehicles with ABS uti-
lize electronic brake distribution which is controlled
through the ABS integrated control unit.
Vehicles not equipped with ABS use a height sens-
ing proportioning valve. It is mounted to the body of
the vehicle above the rear axle (Fig. 91). It has an
actuator lever that attaches to the rear axle and
moves with the axle to help the valve sense the vehi-
cle height.
CAUTION: The height sensing proportioning valve
is not adjustable. No attempt should be made to
adjust it. It is replaced as a complete assembly.
CAUTION: The use of after-market load leveling or
load capacity increasing devices on this vehicle are
prohibited. Using air shock absorbers or helper
springs on this vehicle will cause the height sens-
ing proportioning valve to inappropriately reduce
the hydraulic pressure to the rear brakes. This inap-
propriate reduction in hydraulic pressure potentially
could result in increased stopping distance of the
vehicle.
Fig. 90 Vacuum Seal (Typical)
1 - MASTER CYLINDER ASSEMBLY
2 - VACUUM SEAL
Fig. 91 HEIGHT SENSING PROPORTIONING VALVE
1 - PROPORTIONING VALVE
2 - ACTUATOR LEVER
3 - AXLE BRACKET
4 - REAR AXLE
5 - 56 BRAKES - BASERS
POWER BRAKE BOOSTER (Continued)
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OPERATION - PROPORTIONING VALVE
(HEIGHT SENSING)
Vehicles not equipped with ABS use a height sens-
ing proportioning valve.
The height sensing proportioning valve operates
similarly to a standard proportioning valve in the fol-
lowing way. As hydraulic pressure is applied to the
valve, full input hydraulic pressure is supplied to the
rear brakes up to a certain pressure point, called the
split point. Beyond the split point, the proportioning
valve reduces the amount of hydraulic pressure to
the rear brakes according to a given ratio. Thus, on
light brake applications, approximately equal
hydraulic pressure will be transmitted to both the
front and rear brakes. Upon heavier brake applica-
tions, the hydraulic pressure transmitted to the rear
brakes will be lower than the front brakes. This will
prevent premature rear wheel lockup and skid.
Here is how the height sensing proportioning valve
differs from a standard proportioning valve. As the
height of the rear suspension changes, the height
sensing portion of the proportioning valve changes
the split point of the proportioning valve. When the
height of the rear suspension is low, the proportion-
ing valve interprets this as extra load and the split
point of the proportioning valve is raised to a higher
pressure to allow for more rear braking. When the
height of the rear suspension is high, the proportion-
ing valve interprets this as a light load and the split
point of the proportioning valve is lowered to a lower
pressure and rear braking is reduced.
The height sensing proportioning valve regulates
the pressure by sensing the load condition of the
vehicle through the movement of the proportioning
valve actuator lever (Fig. 91). As the position of the
rear axle changes, depending on the load the vehicle
is carrying, the movement is transferred to the pro-
portioning valve. The proportioning valve adjusts the
hydraulic pressure accordingly.
The height sensing proportioning valve allows the
brake system to maintain the optimal front to rear
brake balance regardless of the vehicle load condi-
tion. Under a light load condition, hydraulic pressure
to the rear brakes is minimized. As the rear load con-
dition increases, so does the hydraulic pressure to
the rear brakes.
DIAGNOSIS AND TESTING - PROPORTIONING
VALVE (HEIGHT SENSING)
CAUTION: The use of aftermarket load leveling or
load capacity increasing devices on this vehicle is
prohibited. Using air shock absorbers or helper
springs on this vehicle will cause the height sens-
ing proportioning valve to inappropriately reduce
the hydraulic pressure to the rear brakes. This inap-propriate reduction in hydraulic pressure potentially
could result in increased stopping distance of the
vehicle.
When a premature rear wheel skid is obtained on a
brake application, it may be an indication that the
hydraulic pressure to the rear brakes is above the
specified output from the proportioning valve. This
condition indicates a possible malfunction of the
height sensing proportioning valve, which will
require testing to verify that it is properly controlling
the hydraulic pressure allowed to the rear brakes.
Premature rear wheel skid may also be caused by
contaminated front or rear brake linings.
Prior to testing a proportioning valve for function,
check that all tire pressures are correct. Also, ensure
the front and rear brake linings are in satisfactory
condition.It is also necessary to verify that the
brakes shoe assemblies on a vehicle being
tested are either original equipment manufac-
turers (OEM) or original replacement brake
shoe assemblies meeting the OEM lining mate-
rial specification. This vehicles brake system is
not balanced for aftermarket brake shoe assem-
bly lining material.
If both front and rear brakes check OK, proceed
with the following test procedure for the height sens-
ing proportioning valve.
(1) Road test the vehicle to determine which rear
wheel brake is exhibiting premature wheel skid.
(2) Raise vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE)
(3) Remove the chassis brake tube going to the
rear brake in question at the proportioning valve.
Remove the chassis brake tube coming from the junc-
tion block at the proportioning valve (Fig. 92).
(4) Install the appropriate fittings from Pressure
Test Fittings, Special Tool 6833, into the open ports
of the proportioning valve.
(5) Install the previously removed brake lines into
the Pressure Test Fittings. Tighten all tube nuts to
17 N´m (145 in. lbs.).
(6) Install a pressure gauge from Gauge Set, Spe-
cial Tool C-4007-A into the open port on each pres-
sure test fitting. Bleed air out of hose from pressure
test fittings to pressure gauges at the pressure
gauges. Then bleed air out of the brake line being
tested at that rear wheel brake bleeder.
NOTE: Actuator rod is a linear spring and is meant
to flex by design. When rod is raised, it will have
some curvature to it.
(7) Remove the screw fastening the proportioning
valve actuator rod bracket to the rear axle. Raise the
actuator lever to the full-upward position and hold it
there.
RSBRAKES - BASE5-57
PROPORTIONING VALVE (Continued)
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