1996 CHRYSLER VOYAGER brake

FIXED PROPORTIONING VALVE OPERATION
The fixed proportioning valve is made out of alumi-
num and has an integral mounting bracket. The
fixed proportioning valve is non-serviceable compo-
nent and must be replaced as an assembly if found to
be functioning improperly.
The fixed proportioning valve is mounted to the
bottom of the left rear frame rail, just forward of the
rear shock absorber to frame rail mounting location
(Fig. 6). The proportioning valve has 2 inlet ports for
brake fluid coming from the ABS modulator, and 2
outlet ports for brake fluid going to the rear wheel
brakes.
The fixed proportioning valve operates by allowing
full hydraulic pressure to the rear brakes up to a set
point, called the valve's split point. Beyond this split
point the proportioning valve reduces the amount of
hydraulic pressure to the rear brakes according to a
certain ratio.
Thus, on light brake pedal applications the propor-
tioning valve allows approximately equal brake
hydraulic pressure to be supplied to both the front
and rear brakes. On heavier brake pedal applications
though, the proportioning valve will control hydraulic
pressure to the rear brakes, so that hydraulic pres-
sure at the rear brakes will be lower than that at the
front brakes. This controlled hydraulic pressure to
the rear brakes prevents excessive rear wheel ABS
cycling during moderate stops.
HEIGHT SENSING PROPORTIONING VALVE
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 potentiallycould result in increased stopping distance of the
vehicle.
On vehicles not equipped with ABS brakes, the
brake systems hydraulic control unit (HCU) is
replaced by a junction block (Fig. 7). The junction
block is made of aluminum and is mounted to the
front suspension crossmember on the drivers side of
the vehicle in the same location as the (HCU) on an
ABS equipped vehicle. The junction block is perma-
nently attached to its mounting bracket and must be
replaced as an assembly with its mounting bracket.
The junction block is used for diagonally splitting the
brake's hydraulic system.
Vehicles not equipped with ABS brakes use a
height sensing proportioning valve. The height sens-
ing proportioning valve is mounted on the left frame
rail at the rear of the vehicle (Fig. 8). The height
sensing proportioning valve uses an actuator assem-
bly (Fig. 8) to attach the proportioning valve to the
left rear spring for sensing changes in vehicle height.
HEIGHT SENSING PROPORTIONING VALVE OPERATION
The height sensing proportioning valve regulates
the hydraulic pressure to the rear brakes. The pro-
portioning valve regulates the pressure by sensing
the load condition of the vehicle through the move-
ment of the proportioning valve actuator assembly
Fig. 6 Fixed Proportioning Valve Location
Fig. 7 Junction Block Location
Fig. 8 Height Sensing Proportioning Valve
5 - 6 BRAKESNS
DESCRIPTION AND OPERATION (Continued)

(Fig. 8). The actuator assembly is mounted between
the height sensing proportioning valve and the actua-
tor bracket on the left rear leaf spring (Fig. 8). As the
rear height of the vehicle changes depending on the
load the vehicle is carrying the height change is
transferred to the height sensing proportioning valve.
This change in vehicle height is transferred through
the movement of the left rear leaf spring. As the posi-
tion of the left rear leaf spring changes this move-
ment is transferred through the actuator bracket
(Fig. 8) to the actuator assembly (Fig. 8) and then to
the proportioning valve.
Thus, the height sensing proportioning valve
allows the brake system to maintain the optimal
front to rear brake balance regardless of the vehicle
load condition. Under a light load condition, hydrau-
lic pressure to the rear brakes is minimized. As the
load condition of the vehicle increases, so does the
hydraulic pressure to the rear brakes.
The proportioning valve section of the valve oper-
ates by transmitting full input hydraulic pressure to
the rear brakes up to a certain 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 certain ratio. Thus, on light
brake applications, approximately equal hydraulic
pressure will be transmitted to the front and rear
brakes. At heavier brake applications, the hydraulic
pressure transmitted to the rear brakes will be lower
then the front brakes. This will prevent premature
rear wheel lock-up and skid.
The height sensing section of the valve thus
changes the split point of the proportioning valve,
based on the rear suspension height of the vehicle.
When the height of the rear suspension is low, the
proportioning valve interprets this as extra load and
the split point of the proportioning valve is raised to
allow more rear braking. When the height of the rear
suspension is high, the proportioning valve interprets
this as a lightly loaded vehicle and the split point of
the proportioning valve is lowered and rear braking
is reduced.
CHASSIS TUBES AND HOSES
The purpose of the chassis brake tubes and flex
hoses is to transfer the pressurized brake fluid devel-
oped by the master cylinder to the wheel brakes of
the vehicle. The chassis tubes are steel with a corro-
sion resistant coating applied to the external surfaces
and the flex hoses are made of reinforced rubber. The
rubber flex hoses allow for the movement of the vehi-
cles suspension.
MASTER CYLINDER
The master cylinder (Fig. 9) consists of the follow-
ing components. The body of the master cylinder isan anodized aluminum casting. It has a machined
bore to accept the master cylinder piston and
threaded ports with seats for the hydraulic brake
line connections. The brake fluid reservoir of the
master cylinder assembly is made of a see through
polypropylene type plastic. A low fluid switch is also
part of the reservoir assembly.
This vehicle uses 3 different master cylinders.
Master cylinder usage depends on what type of brake
system the vehicle is equipped with. If a vehicle is
not equipped with antilock brakes, or is equipped
with antilock brakes without traction control, a con-
ventional compensating port master cylinder is used.
If a vehicle is equipped with antilock brakes with
traction control, a dual center port master cylinder is
used.
The third master cylinder used on this vehicle is
unique to vehicles equipped with four wheel disc
brakes. The master cylinder used for this brake
application has a different bore diameter and stroke
then the master cylinder used for the other available
brake applications.
The master cylinders used on front wheel drive
applications (non four wheel disc brake vehicles)
have a master cylinder piston bore diameter of 23.8
mm. The master cylinder used on the all wheel drive
applications (four wheel disc brake vehicles) have a
master cylinder piston bore diameter of 25.4 mm.
When replacing a master cylinder, be sure to
use the correct master cylinder for the type of
brake system the vehicle is equipped with.
The master cylinder is not a repairable component
and must be replaced if diagnosed to be functioning
improperly
CAUTION: Do not hone the bore of the cylinder as
this will remove the anodized surface from the bore.
The master cylinder primary outlet port supplies
hydraulic pressure to the right front and left rear
Fig. 9 Master Cylinder Assembly
NSBRAKES 5 - 7
DESCRIPTION AND OPERATION (Continued)

brakes. The secondary outlet port supplies hydraulic
pressure to the left front and right rear brakes.
POWER BRAKE VACUUM BOOSTER OPERATION
All vehicles use a 270 mm single diaphragm power
brake vacuum booster.
The power brake booster can be identified if
required, by the tag attached to the body of the
booster assembly (Fig. 10). This tag contains the fol-
lowing information: The production part number of
the power booster assembly, the date it was built,
and who was the manufacturer of the power brake
vacuum booster.
NOTE: The power brake booster assembly is not a
repairable component and must be replaced as a
complete assembly if it is found to be faulty in any
way. The check valve located in the power brake
booster (Fig. 10) is not repairable but it can be
replaced as an assembly separate from the power
brake booster.
The power brake booster reduces the amount of
force required by the driver to obtain the necessary
hydraulic pressure to stop vehicle.
The power brake booster is vacuum operated. The
vacuum is supplied from the intake manifold on the
engine through the power brake booster check valve
(Fig. 10) and (Fig. 11).
As the brake pedal is depressed, the power brake
boosters input rod moves forward (Fig. 11). This
opens and closes valves in the power booster, allow-
ing atmospheric pressure to enter on one side of a
diaphragm. Engine vacuum is always present on the
other side. This difference in pressure forces the out-
put rod of the power booster (Fig. 11) out against the
primary piston of the master cylinder. As the pistons
in the master cylinder move forward this creates the
hydraulic pressure in the brake system.The different engine combinations used on this
vehicle require that different vacuum hose routings
to the power brake vacuum booster be used.
All vacuum hoses must be routed from the engine
to the power brake vacuum booster without kinks,
excessively tight bends or potential for damage to the
vacuum hose.
The power brake vacuum booster assembly mounts
on the engine side of the dash panel, and is con-
nected to the brake pedal by the input push rod (Fig.
11). A vacuum line connects the power booster to the
intake manifold. The master cylinder is bolted to the
front of the power brake vacuum booster assembly.
RED BRAKE WARNING LAMP OPERATION
The red Brake warning lamp is located in the
instrument panel cluster and is used to indicate a
low brake fluid condition or that the parking brake is
applied. In addition, the brake warning lamp is
turned on as a bulb check by the ignition switch
every time the ignition switch is turned to the crank
position.
The warning lamp bulb is supplied a 12 volt igni-
tion feed anytime the ignition switch is on. The bulb
is then illuminated by completing the ground circuit
either through the park brake switch, the fluid level
sensor in the master cylinder reservoir, or the igni-
tion switch when it is turned to the crank position.
The Brake Fluid Level sensor is located in the
brake fluid reservoir of the master cylinder assembly.
The purpose of the sensor is to provide the driver
with an early warning that brake fluid level in the
master cylinder fluid reservoir has dropped to below
Fig. 10 Power Brake Booster Identification
Fig. 11 Power Brake Booster Assembly
5 - 8 BRAKESNS
DESCRIPTION AND OPERATION (Continued)

normal. This may indicate:(1)Abnormal loss of
brake fluid in the master cylinder fluid reservoir
resulting from a leak in the hydraulic system.(2)
Brake shoe linings which have worn to a point
requiring replacement.
As the brake fluid drops below the minimum level,
the brake fluid level sensor closes to ground the
brake warning light circuit. This will turn on the red
brake warning light. At this time, master cylinder
fluid reservoir should be checked and filled to the full
mark with DOT 3 brake fluid.If brake fluid level
has dropped below the add line in the master
cylinder fluid reservoir, the entire brake
hydraulic system should be checked for evi-
dence of a leak.
STOP LAMP SWITCH
The stop lamp switch controls operation of the
vehicles stop lamps. Also, if the vehicle is equippedwith speed control, the stop lamp switch will deacti-
vate speed control when the brake pedal is
depressed.
The stop lamp switch controls operation of the
right and left tail, stop and turn signal lamp and
CHMSL lamp, by supplying battery current to these
lamps.
The stop lamp switch controls the lamp operation
by opening and closing the electrical circuit to the
stop lamps.
HUB/BEARING REAR WHEEL
The rear hub and bearing assembly used on this
vehicle is serviceable only as a complete assembly. No
attempt should be made to disassemble a rear hub
and bearing assembly in an effort to repair it.
The rear hub and bearing assembly is attached to
the rear axle using 4 mounting bolts that are remov-
able from the back of the rear hub/bearing.
DIAGNOSIS AND TESTING
BRAKE SYSTEM BASIC DIAGNOSIS GUIDE
SYMPTOMCHART 1
MISC.
COND.CHART 2
WARNING
LIGHTCHART 3
POWER
BRAKESCHART 4
BRAKE
NOISECHART 5
WHEEL
BRAKES
Brake Warning Light On X NO NO
Excessive Pedal Travel 6 X NO O
Pedal Goes To The Floor 6 X
Stop Light On Without Brakes 3
All Brakes Drag 5
Rear Brakes Drag 2 NO NO
Grabby Brakes O X
Spongy Brake Pedal X NO
Premature Rear Brake Lockup 4 NO NO O
Excessive Pedal Effort 1 O
Rough Engine Idle NO O
Brake Chatter (Rough) NO NO X
Surge During Braking NO NO X
Noise During Braking NO NO X
Rattle Or Clunking Noise NO NO X
Pedal Pulsates During Braking NO NO X
Pull To Right Or Left NO NO X
No: Not A Possible Cause X: Most Likely Cause O: Possible Cause
NSBRAKES 5 - 9
DESCRIPTION AND OPERATION (Continued)

BRAKE SYSTEM DIAGNOSIS CHARTS
MISCELLANEOUS BRAKE SYSTEM CONDITIONS
5 - 10 BRAKESNS
DIAGNOSIS AND TESTING (Continued)

RED BRAKE WARNING LAMP FUNCTION
NSBRAKES 5 - 11
DIAGNOSIS AND TESTING (Continued)

POWER BRAKE SYSTEM DIAGNOSTICS
5 - 12 BRAKESNS
DIAGNOSIS AND TESTING (Continued)

VEHICLE ROAD TEST
BRAKE NOISE
NSBRAKES 5 - 13
DIAGNOSIS AND TESTING (Continued)