Chrysler Town, Dodge Caravan. Manual — part 48
If the vacuum supply is 12 inches Hg (40.5 kPa) or
more, the power brake booster is defective and must
be replaced. If the vacuum supply is below 12 inches
Hg, continue on with this BASIC TEST.
(6) Shut off the engine.
(7) Connect the vacuum gauge to the vacuum ref-
erence port on the engine intake manifold.
(8) Start the engine and observe the vacuum
gauge.
If the vacuum is still low, check the engine tune
and repair as necessary. If the vacuum is above 12
inches Hg, the hose or check valve to the booster has
a restriction or leak.
Once an adequate vacuum supply is obtained,
repeat the BASIC TEST.
VACUUM LEAK TEST
(1) Disconnect the vacuum hose on the vacuum
check valve, then place a vacuum gauge in line
between the vacuum hose and the valve.
(2) Start the engine.
(3) Allow the engine to warm up to normal operat-
ing temperature and engine idle.
(4) Using vacuum line pliers, close off the vacuum
supply hose near the booster, but before the vacuum
gauge, then observe the vacuum gauge.
If the vacuum drop exceeds 1.0 inch Hg (3.3 kPa)
in one minute, repeat the above steps to confirm the
reading. The vacuum loss should be less than 1.0
inch Hg in one minute time span. If the loss is more
than 1.0 inch Hg, replace the power brake booster. If
it is not, continue on with this test.
(5) Remove the pliers from the hose temporarily.
(6) Apply light effort (approximately 15 lbs. of
force) to the brake pedal and hold the pedal steady.
Do not move the pedal once the pressure is applied
or the test results may vary.
(7) Have an assistant reattach the vacuum line
pliers to the vacuum supply hose.
(8) Allow 5 seconds for stabilization, then observe
the vacuum gauge.
If the vacuum drop exceeds 3.0 inches Hg (10 kPa)
in 15 seconds, repeat the above steps to confirm the
reading. The vacuum loss should be less than 3.0
inches Hg in 15 seconds time span. If the loss is
more than 3.0 inches Hg, replace the power brake
booster. If it is not, the booster is not defective.
(9) Remove the pliers and vacuum gauge.
REMOVAL
REMOVAL - LHD
CAUTION: Reserve vacuum in power brake booster
must be pumped down (removed) before removing
master cylinder from booster. This is necessary to
prevent booster from sucking in any contamination
as master cylinder is removed. This can be done
simply by pumping the brake pedal, with the vehi-
cle’s engine not running, until a firm feeling brake
pedal is achieved.
(1) With engine not running, pump the brake
pedal until a firm pedal is achieved (4-5 strokes).
(2) Remove negative battery cable terminal from
battery.
(3) Remove positive battery cable terminal from
battery.
(4) Remove battery thermal guard shield.
(5) Remove battery clamp, nut and battery from
the battery tray.
(6) Remove screw securing engine coolant filler
tube to battery tray.
(7) If the vehicle is equipped with speed control,
disconnect the vacuum hose at the vacuum tank built
into the battery tray.
(8) Remove the two nuts and one bolt securing bat-
tery tray in place. Remove battery tray.
(9) If vehicle is equipped with speed control:
(a) Disconnect wiring harness connector from
the speed control servo.
(b) Remove the two servo mounting nuts.
(c) Lay speed control servo off to the side, out of
the way.
(10) Remove the wiper module (unit). (Refer to 8 -
ELECTRICAL/WIPERS/WASHERS/WIPER
MOD-
ULE - REMOVAL)
(11) Disconnect wiring harness connector from
brake fluid level switch in master cylinder fluid res-
ervoir (Fig. 58).
Fig. 58 Master Cylinder And Booster
1 - POWER BRAKE BOOSTER
2 - BOOSTER IDENTIFICATION LABEL
3 - FLUID LEVEL SWITCH CONNECTOR
4 - PRIMARY BRAKE TUBE NUT
5 - SECONDARY BRAKE TUBE NUT
6 - MASTER CYLINDER
5 - 42
BRAKES - BASE
RS
POWER BRAKE BOOSTER (Continued)
CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.
(12) Clean area where master cylinder assembly
attaches to power brake booster. Use only a solvent
such as Mopar
t Brake Parts Cleaner or equivalent.
(13) Disconnect
primary
and
secondary
brake
tubes from ABS integrated control unit or non-ABS
junction block (Fig. 59). Install sealing plugs in the
now open brake tube ports and install caps on ends
of tubes.
NOTE: It is not necessary to remove the brake
tubes from the master cylinder when removing the
master cylinder from the vacuum booster.
(14) Remove two nuts attaching master cylinder to
power brake booster (Fig. 59).
(15) Slide master cylinder straight out of power
brake booster. Remove master cylinder with primary
and secondary tubes from vehicle.
CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.
(16) Disconnect vacuum hose from check valve
located on vacuum booster. DO NOT REMOVE
CHECK
VALVE
FROM
POWER
BRAKE
BOOSTER.
(17) Inside vehicle, remove silencer panel under
instrument panel below steering column.
(18) Locate the booster input rod to brake pedal
connection under the instrument panel. Position a
small screwdriver between the center tang on the
power brake booster input rod to brake pedal pin
retaining clip (Fig. 60).
(19) Rotate screwdriver enough to allow retaining
clip center tang to pass over end of brake pedal pin.
Then pull retaining clip off brake pedal pin. Discard
retaining clip. It is not to be reused. Replace
only with a new retaining clip when assem-
bling.
(20) Slide booster input rod off pedal pin.
(21) Remove the four nuts attaching power brake
booster to dash panel (Fig. 61).
(22) Slide power brake booster forward and remove
through engine compartment (Fig. 62).
CAUTION: Do not attempt to disassemble the power
brake vacuum booster. It is serviced ONLY as a
complete assembly.
REMOVAL - RHD
CAUTION: Reserve vacuum in power brake booster
must be pumped down (removed) before removing
master cylinder from booster. This is necessary to
prevent booster from sucking in any contamination
as master cylinder is removed. This can be done
simply by pumping the brake pedal, with the vehi-
cle’s engine not running, until a firm feeling brake
pedal is achieved.
Fig. 59 Master Cylinder Mounting
1 - MASTER CYLINDER MOUNTING NUTS
2 - MASTER CYLINDER
3 - SECONDARY TUBE NUT AT ICU
4 - PRIMARY TUBE NUT AT ICU
Fig. 60 Vacuum Booster Input Rod Retaining Pin
1 - BRAKE PEDAL
2 - INPUT ROD
3 - SCREWDRIVER
4 - RETAINING CLIP
5 - BRAKE PEDAL PIN
RS
BRAKES - BASE
5 - 43
POWER BRAKE BOOSTER (Continued)
(1) With engine not running, pump the brake
pedal until a firm pedal is achieved (4 or 5 strokes).
(2) Remove negative battery cable terminal from
battery.
(3) Remove positive battery cable terminal from
battery.
(4) Remove battery thermal guard shield.
(5) Remove battery clamp, nut and battery from
the battery tray.
(6) If the vehicle is equipped with speed control,
disconnect the vacuum hose at the vacuum tank built
into the battery tray.
(7) Remove the two nuts and one bolt securing bat-
tery tray in place. Remove battery tray.
(8) If vehicle is equipped with speed control:
(a) Disconnect wiring harness connector from
the speed control servo.
(b) Remove the two servo mounting nuts.
(c) Lay speed control servo off to the side, out of
the way.
(9) If the vehicle is equipped with the 2.5L diesel
engine, remove the coolant recovery pressure con-
tainer and bracket. (Refer to 7 - COOLING/ENGINE/
COOLANT
RECOVERY
PRESS
CONTAINER
-
REMOVAL)
(10) Disconnect wiring harness connector from
brake fluid level switch in master cylinder fluid res-
ervoir (Fig. 63).
CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.
(11) Clean area where master cylinder assembly
attaches to power brake booster. Use only a solvent
such as Mopar
t Brake Parts Cleaner or equivalent.
NOTE: It is not necessary to remove the brake
tubes from the master cylinder when removing the
master cylinder from the booster.
(12) Remove two nuts attaching master cylinder to
power brake booster (Fig. 64).
(13) Slide master cylinder straight out of power
brake booster. Lay master cylinder with primary and
secondary tubes to the side, out of the way.
Fig. 61 Booster Mounting
1 - DASH BRACKET
2 - POWER BRAKE BOOSTER
3 - BRAKE PEDAL ASSEMBLY
Fig. 62 Booster Removal/Installation
Fig. 63 RHD Master Cylinder And Power Brake
Booster
1 - POWER BRAKE BOOSTER
2 - BRAKE FLUID LEVEL SWITCH
3 - FLUID RESERVOIR
4 - MASTER CYLINDER
5 - 44
BRAKES - BASE
RS
POWER BRAKE BOOSTER (Continued)
CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.
(14) Disconnect vacuum hose from check valve
located on booster. DO NOT REMOVE CHECK
VALVE FROM POWER BRAKE BOOSTER.
(15) Under the instrument panel, remove booster
input rod trim cover.
(16) Locate the booster input rod to brake pedal
torque shaft connection under the instrument panel.
Position a small screwdriver between the center tang
on the retaining clip (Fig. 65).
(17) Rotate screwdriver enough to allow retaining
clip center tang to pass over end of brake pedal pin.
Then pull retaining clip off brake pedal torque shaft
pin. Discard retaining clip. It is not to be
reused. Replace only with a new retaining clip
when assembling.
(18) Remove booster input rod from pedal torque
shaft pin.
(19) Remove the three easily accessed mounting
nuts attaching power brake booster to dash panel
and loosen fourth (Fig. 66). As fourth nut is loosened,
push the booster forward periodically until the nut
can be completely removed.
(20) Slide power brake booster forward and remove
through engine compartment (Fig. 67).
CAUTION: Do not attempt to disassemble the power
brake vacuum booster. It is serviced ONLY as a
complete assembly.
Fig. 64 RHD Master Cylinder Mounting
1 - PRIMARY BRAKE TUBE NUT
2 - SECONDARY BRAKE TUBE NUT
3 - MASTER CYLINDER MOUNTING NUTS
Fig. 65 Booster Input Rod Pin Retaining Clip
(Typical)
1 - BRAKE PEDAL
2 - INPUT ROD
3 - SCREWDRIVER
4 - RETAINING CLIP
5 - BRAKE PEDAL PIN
Fig. 66 Booster, Torque Shaft And Pedal Mounting
1 - PEDAL MOUNTING NUT
2 - BRAKE PEDAL ASSEMBLY
3 - PEDAL MOUNTING NUT
4 - PEDAL TORQUE SHAFT
5 - BOOSTER MOUNTING NUT
6 - BOOSTER BRACKET
7 - POWER BRAKE BOOSTER
8 - BOOSTER BRACKET MOUNTING NUT
RS
BRAKES - BASE
5 - 45
POWER BRAKE BOOSTER (Continued)
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