seat JEEP CHEROKEE 1995 Service Owner's Guide

(2) Disconnect brake lines at master cylinder and
combination valve.
(3) Remove nuts attaching master cylinder to
booster studs.
(4) Remove master cylinder.
(5) Remove cylinder cover and drain fluid.
(6) If two-piece master cylinder reservoir requires
service, refer to reservoir replacement procedure in
this section.
MASTER CYLINDER INSTALLATION (NON-ABS)
(1) Bleed master cylinder on bench before installa-
tion. Refer to procedure in this section.
(2) If new two-piece master cylinder is being in-
stalled, remove plastic protective sleeve from primary
piston shank. Also check condition of seal at rear of
cylinder body. Reposition seal if dislodged. Replace
seal if cut, or torn.
(3) Clean cylinder mounting surface of brake booster.
Use shop towel wetted with brake cleaner for this pur-
pose. Dirt, grease, or similar materials will prevent
proper cylinder seating and could result in vacuum leak.
(4) Slide master cylinder onto brake booster studs.
(5) Install nuts attaching master cylinder to booster
studs. Tighten nuts to 25 Nzm (220 in. lbs.) torque.
(6) Connect brakelines to master cylinder and com-
bination valve (Figs. 1 and 2).
(7) Fill and bleed brake system.
COMBINATION VALVE REPLACEMENT (NON-ABS)
The combination valve is not a repairable compo-
nent. The valve is serviced as an assembly whenever
diagnosis indicates replacement is necessary.
(1) Remove air cleaner cover and hose for access to
valve, if necessary.
(2) Disconnect differential pressure switch wire at
combination valve. Do not pull switch wire to discon-
nect. Unsnap connecter lock tabs to remove.
(3) Disconnect brakelines at combination valve and
remove valve.
(4) Connect brakelines to replacement valve. Start
line fittings by hand to avoid cross threading.
Tighten fittings snug but not to required torque at
this time.
(5) Connect wire to pressure differential switch.
(6) Bleed brakes.
(7) Tighten brakeline fittings to 18-24 Nzm
(160-210 in. lbs.) torque after bleeding.
MASTER CYLINDER OVERHAUL (4-CYLINDER
MODELS)
CYLINDER DISASSEMBLY
(1) Examine cylinder cover seal. Discard seal if
torn or distorted.
(2) Clamp cylinder in vise (Fig. 3).(3) Remove piston retaining snap ring. Press and
hold primary piston inward with wood dowel or sim-
ilar tool. Then remove snap ring (Fig. 4).
(4) Remove and discard primary piston (Fig. 5).
Piston is serviced only as assembly.
(5) Remove secondary piston (Fig. 6). Apply air
pressure through rear outlet port to ease piston out
of bore. Cover small ports at bottom of rear reservoir
with towel to prevent air leakage.
(6) Discard secondary piston. Do not disassemble
piston as components are only serviced as assembly.
MASTER CYLINDER CLEANING AND
INSPECTION
Clean the cylinder with Mopar brake cleaning sol-
vent or clean brake fluid. Remove cleaning residue
with compressed air.
Inspect the cylinder bore. A light discoloration of
Fig. 3 Mounting Cylinder In Vise
Fig. 4 Removing/Installing Piston Snap Ring
5 - 16 MASTER CYLINDERÐCOMBINATION VALVEJ

(5) Remove air cleaner housing from engine com-
partment.
(6) Disconnect wire from combination valve pres-
sure differential switch (Fig. 9). Do not pull wire to
disconnect. Unsnap lock tabs on wire connecter.
(7) Disconnect canister vacuum line at manifold
fitting (Fig. 10).
(8) Disconnect brake booster vacuum hose at in-
take manifold fitting (Fig. 11). Move hose aside for
working clearance.(9) Unseat small S-clip that secures brakelines
(Fig. 12).
(10) Remove brakeline that connects master cylin-
der front port to combination valve front port (Fig.
12).
(11) Disconnect master cylinder rear brakeline at
cylinder. Then loosen line at combination valve and
swing line around to opposite side of cylinder (Fig.
13).
(12) Disconnect rear brakeline at HCU (Fig. 14).
(13) Disconnect both flex brakelines at HCU (Fig.
14).
(14) Disconnect HCU line to rear brakes at HCU
port (Fig. 14).
(15) Remove nut attaching combination valve
bracket to brake booster stud.
(16) Remove combination valve and brakelines as
assembly (Fig. 15). Work valve bracket off booster
stud. Then work brakelines around cylinder and
HCU and remove assembly.
Fig. 9 Pressure Differential Switch Wire Connection
Fig. 10 Canister Vacuum Line Location (At Manifold
Fitting)
Fig. 11 Booster Vacuum Hose Removal/Installation
(From Manifold Fitting)
Fig. 12 Master Cylinder Front Brakeline Removal/
Installation
Fig. 13 Disconnecting Master Cylinder Rear
Brakeline
5 - 18 MASTER CYLINDERÐCOMBINATION VALVEJ

(5) Remove reservoir by rocking it to one side and
pulling free of grommets (Fig. 19).
(6) Remove old grommets from cylinder body (Fig.
20).
(7) Lubricate new grommets with clean brake
fluid.
(8) Install new grommets in cylinder body (Fig.
21). Use finger pressure only to install and seat
grommets.
CAUTION: Do not use any type of tool to install the
grommets. Tools may cut, or tear the grommets cre-
ating a leak problem after installation. Install the
grommets using finger pressure only.(9) Start reservoir in grommets. Then rock reser-
voir back and forth while pressing downward to seat
it in grommets.
(10) Install pins that retain reservoir to cylinder
body (Fig. 17).
(11) Fill and bleed master cylinder on bench before
installation in vehicle.
MASTER CYLINDER AND COMBINATION VALVE
INSTALLATION (WITH ABS)
(1) Bleed master cylinder on bench before installa-
tion. Refer to procedure in this section.
(2) If new master cylinder is being installed, re-
move plastic protective sleeve from primary piston
shank.
(3) If original master cylinder is being installed,
check condition of seal at rear of master cylinder
(Fig. 22). Clean and reposition seal if dislodged. Re-
place seal if cut, or torn.
(4) Clean cylinder mounting surface of brake
booster (Fig. 23). Use shop towel wetted with brake
cleaner for this purpose. Dirt, grease, or similar ma-
terials will prevent proper cylinder seating and could
result in vacuum leak.
(5) If new master cylinder is being installed,re-
move plastic protective sleeve from piston
shank before installation.
(6) Position master cylinder on booster studs (Fig.
24). Then install and tighten cylinder attaching nuts
to 25 Nzm (220 in. lbs.) torque.
Fig. 19 Reservoir Removal
Fig. 20 Grommet Removal
Fig. 21 Grommet Installation
Fig. 22 Checking Master Cylinder Seal
Fig. 23 Cylinder Mounting Surface Of Brake Booster
5 - 20 MASTER CYLINDERÐCOMBINATION VALVEJ

POWER BRAKE BOOSTER REMOVAL
(XJ WITH ABS)
(1) Disconnect vacuum and vent hoses at air
cleaner cover.
(2) Loosen clamp securing air cleaner hose to in-
take manifold. Use screwdriver to tap clamp loose.
(3) Remove air cleaner cover and hose. Then re-
move air filter from air cleaner housing (Fig. 4).
(4) Remove two bolts and one nut that secure air
cleaner housing to body (Fig. 4).
(5) Remove air cleaner housing from engine com-
partment (Fig. 4).
(6) Disconnect wire at combination valve pressure
differential switch (Fig. 5). Do not pull on wires to
disconnect. Unsnap lock tabs on connecter to remove
wires.
(7) Disconnect canister vacuum line at manifold
fitting (Fig. 6).(8) Disconnect brake booster vacuum hose at in-
take manifold fitting (Fig. 7). Move hose aside for
working clearance.
(9) Unseat small S-clip that secures brakelines
(Fig. 8).
(10) Remove front brakeline that connects master
cylinder front port to combination valve front port
(Fig. 8).
Fig. 3 Power Brake Booster Internal Components
5 - 24 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

POWER BRAKE BOOSTER INSTALLATION (XJ WITH
ABS)
(1) If new booster is being installed, install new
check valve and vacuum hose (Fig. 17). Also install
dash seal and spacer on new booster, if equipped.
(2) Position booster on dash panel (Fig. 17) seat
booster studs in dash panel holes.
(3) Working inside vehicle, install nuts on booster
mounting studs. Tighten nuts just enough to hold
booster in place.
(4) Attach booster push rod to brake pedal. Secure
push rod with retainer clip.
(5) Tighten booster attaching nuts to 41 Nzm (30 ft.
lbs.) on XJ and 34 Nzm (25 ft. lbs.) on YJ.
(6) If necessary, bleed master cylinder on bench be-
fore installation. Refer to procedure in master cylin-
der section.
(7) If new master cylinder is being installed,re-
move plastic protective sleeve from primary
piston shank.
Fig. 13 Disconnecting HCU Solenoid Harness
Fig. 14 Disconnecting HCU Pump Harness
Fig. 15 HCU Front/Rear Brakeline Connections
Fig. 16 Push Rod Attachment At Brake Pedal
Fig. 17 Brake Booster Positioned On Dash Panel
JPOWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCH 5 - 27

(8) Check condition of seal at rear of master cylin-
der (Fig. 22). Clean and reposition seal if dislodged.
Replace seal if cut, or torn.
(9) Clean cylinder mounting surface of brake
booster (Fig. 19). Use shop towel wetted with brake
cleaner for this purpose. Dirt, grease, or similar ma-
terials will prevent proper cylinder seating and could
result in vacuum leak.
(10) Position master cylinder on booster studs (Fig.
20).Be sure booster push rod is centered and
seated in master cylinder piston shank.
(11) Install and tighten master cylinder attaching
nuts to 25 Nzm (220 in. lbs.) torque.(12) Install HCU as follows:
(a) If only the HCU was removed, position HCU
in mounting bracket. Then install and tighten
three shoulder bolts that attach HCU to bracket
(Figs. 21 and 22). One bolt is used at forward end
of bracket and two at rear as shown.
(b) If HCU and bracket were removed as assem-
bly, position bracket on studs and install attaching
nuts. Tighten nuts to 10-13 Nzm (92-112 in. lbs.)
torque.
(c) On right hand drive models, If brackets were
removed, assemble brackets. Then position lower
bracket on body studs and install attaching nuts
and the one attaching bolt (Fig. 23).
(13) If HCU mounting bracket was not removed,
press solenoid harness connecter fasteners into
mounting bracket holes.
(14) Connect HCU pump motor and solenoid har-
nesses (Figs. 13 and 14).
(15) Connect brakelines to HCU. Start brakeline
fittings in HCU ports by hand to avoid cross thread-
ing (Fig. 24). Then tighten line fittings snug but not
to required torque at this time.
Fig. 18 Checking Master Cylinder Seal
Fig. 19 Cylinder Mounting Surface Of Brake Booster
Fig. 20 Master Cylinder Installation
Fig. 21 Installing HCU Front Shoulder Bolt
Fig. 22 Installing HCU Rear Shoulder Bolts
5 - 28 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

(11) Remove nuts attaching booster to passenger
compartment side of dash panel.
(12) In engine compartment, slide booster studs
out of dash panel, tilt booster upward, and remove
booster from engine compartment.
(13) Remove dash seal from booster.
(14) If booster is only being removed for access to
other components, cover booster front opening with
clean shop towel.
POWER BRAKE BOOSTER INSTALLATION (XJ
WITHOUT ABS)
(1) If original booster is being installed, test check
valve with vacuum tool before booster installation.
Replace check valve if it will not hold vacuum.
(2) Install dash seal on booster.
(3) Align and position booster on dash panel (Fig.
17).
(4) In passenger compartment, install nuts that at-
tach booster to dash panel. Tighten nuts just enough
to hold booster in place.
(5) Slide booster push rod onto brake pedal. Then
secure push rod to pedal pin with retaining clip.
(6) Tighten booster attaching nuts to 41 Nzm (30 ft.
lbs.) on XJ and 34 Nzm (25 ft. lbs.) on YJ.
(7) Install instrument panel lower trim cover.
(8) If original master cylinder is being installed,
check condition of seal at rear of master cylinder
(Fig. 18). Clean and reposition seal if dislodged. Re-
place seal if cut, or torn.
(9) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
this purpose. Dirt, grease, or similar materials will
prevent proper cylinder seating and could result in
vacuum leak.
(10) Align and install master cylinder on booster
studs. Tighten cylinder attaching nuts to 13-25 Nzm
(115-220 in. lbs.) torque.
(11) Connect vacuum hose to booster check valve.
(12) Connect and secure brakelines to combination
valve and master cylinder. Start all brakeline fittings
by hand to avoid cross threading.
(13) If combination valve has integral bracket, po-
sition bracket on booster studs. Then install and
tighten bracket attaching nuts to 13-25 Nzm (115-220
in. lbs.) torque.
(14) Connect wire to combination valve switch.
(15) Top off master cylinder fluid level.
(16) Bleed brakes. Refer to procedures in section
on brake bleeding.
(17) Install engine air cleaner and hoses.
(18) Verify proper brake operation before moving
vehicle.
POWER BRAKE BOOSTER REMOVAL (YJ)
(1) Disconnect brakelines at master cylinder. Then
loosen lines at combination valve and move lines
away from cylinder.
(2) Remove nuts master cylinder to booster studs.
(3) If combination valve has integral bracket, slide
bracket off studs and move valve aside.
(4) Remove master cylinder. Slide cylinder off
studs and remove it from engine compartment.
(5) Working under instrument panel, remove re-
tainer clip that secures booster push rod to brake
pedal.
(6) Disconnect vacuum hose at booster check valve.
(7) On non-ABS models, remove nuts attaching
brake booster spacer to dash panel and remove
booster (Fig. 26).
(8) On ABS models, remove nuts attaching booster
to spacer and remove booster (Fig. 27).
POWER BRAKE BOOSTER INSTALLATION (YJ)
(1) Install seal on booster spacer, if equipped.
(2) Position booster on dash panel, or on spacer.
(3) Secure booster push rod to brake pedal with re-
taining clip.
(4) Install and tighten booster attaching nuts to
27-47 Nzm (20-35 ft. lbs.) torque. Nut torque applies
to both styles of booster.
Fig. 26 Booster Mounting (4-Cyl. Models)
Fig. 27 Booster Mounting (With ABS)
5 - 30 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

BRAKELIGHT SWITCH REMOVAL
The brakelight switch is mounted in the pedal sup-
port bracket and is operated by the pedal. The switch
is secured in the bracket with a retainer (Fig. 30).
(1) Remove steering column cover and lower trim
panel for switch access, if necessary.
(2) Disconnect switch wire harness.
(3) Thread switch out of retainer, or rock switch
up/down and pull it rearward out of retainer.
(4) Inspect switch retainer, if equipped. Replace re-
tainer if worn, distorted, loose, or damaged.
BRAKELIGHT SWITCH INSTALLATION
(1) Insert replacement switch in retainer. Thread
switch into place or rock it up/down until switch
plunger touches brake pedal. Insert switch in bracket
and thread clip onto plunger to secure switch.
(2) Connect switch wires.
(3) Check switch operation. Adjust switch position
if necessary. Refer to procedures in this section.
(4) Install trim panels (if removed).
BRAKELIGHT SWITCH ADJUSTMENT
A plunger-type brakelight switch is used on XJ and
YJ models (Fig. 30). The switch plunger is actuated
directly by the brake pedal.
The switch internal contacts are open when the
brake pedal is in the released position. Brake appli-
cation moves the pedal away from the switch allow-
ing the plunger to extend. As the plunger extends,
the switch internal contacts close completing the cir-
cuit to the brakelights.
The switch is retained in the bracket by a clip. The
clip has tangs that seat in the threads of the switch
plunger barrel.
SWITCH ADJUSTMENT PROCEDURE
(1) Check switch adjustment. Move the brake
pedal forward by hand and note operation of the
switch plunger. Plunger should extend when pedalfree play is taken up and brake application begins. A
clearance of approximately 3 mm (1/8 in.) should ex-
ist between plunger and pedal at this point.
(a) If switch-to-pedal clearance is OK and brake-
lights operate correctly, adjustment is not required.
(b) If switch plunger does not extend and clear-
ance between pedal and plunger is insufficient, ad-
just switch position as described in step (2).
(2) Grasp brake pedal and pull it rearward as far
as possible. Switch plunger barrel will ``ratchet'' rear-
ward in retaining clip to correct position.
(3) Verify brakelight switch operation and proper
clearance between switch plunger and brake pedal.
CAUTION: Be very sure the brake pedal returns to a
fully released position after adjustment. The switch
can interfere with full pedal return if too far forward.
The result will be brake drag caused by partial
brake application.
Fig. 30 Brakelight Switch Mounting And Location
(XJ/YJ)
5 - 32 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

air gap should be 0.40 to 1.3 mm (0.0157 to 0.051
in.). If gap is incorrect, the sensor is either loose, or
damaged.
A rear sensor air gap adjustment is only needed
when reinstalling an original sensor. Replacement
sensors have an air gap spacer attached to the sensor
pickup face. The spacer establishes correct air gap
when pressed against the tone ring during installa-
tion. As the tone ring rotates, it peels the spacer off
the sensor to create the required air gap. Rear sensor
air gap is 0.92-1.45 mm (0.036-0.057 in.).
Sensor air gap measurement, or adjustment proce-
dures are provided in this section. Refer to the front,
or rear sensor removal and installation procedures as
required.
FRONT WHEEL SENSOR REMOVAL
(1) Raise vehicle and turn wheel outward for easier
access to sensor.
(2) Remove sensor wire from mounting brackets.
(3) Clean sensor and surrounding area with shop
towel before removal.
(4) Remove bolt attaching sensor to steering
knuckle and remove sensor.
(5) remove sensor wire from brackets on body and
steering knuckle.
(6) Unseat sensor wire grommet in wheel house
panel.
(7) In engine compartment, disconnect sensor wire
connector at harness plug. Then remove sensor and
wire.
FRONT WHEEL SENSOR INSTALLATION
(1) Iforiginalsensor will be installed, wipe all
traces of old spacer material off sensor pickup face.
Use a dry shop towel for this purpose.
(2) Apply Mopar Lock N' Seal or Loctite 242 to bolt
that secures sensor in steering knuckle. Use new
sensor bolt if original bolt is worn or damaged.
(3) Position sensor on steering knuckle. Seat sen-
sor locating tab in hole in knuckle and install sensor
attaching bolt finger tight.
(4) Tighten sensor attaching bolt to 14 Nzm (11 ft.
lbs.) torque.
(5) If original sensor has been installed, check sen-
sor air gap. Air gap should be 0.40 to 1.3 mm (0.0157
to 0.051 in.). If gap is incorrect, sensor is either loose,
or damaged.
(6) Secure sensor wire to steering knuckle and
body brackets.
(7) Route sensor wire forward and behind shock
absorber. Then attach sensor wire to spring seat
bracket with grommets on sensor wire.
(8) Route sensor wire to outer sill bracket. Remove
all twists or kinks from wire.
(9) Attach sensor wire to sill bracket with grom-
met. Be sure wire is free of twists and kinks.(10) Verify sensor wire routing. Wire should loop
forward and above sill bracket. Loose end of wire
should be below sill bracket and towards brake hose.
(11) Seat sensor wire grommet in body panel and
clip wire to brake line at grommet location.
(12) Connect sensor wire to harness in engine com-
partment.
REAR WHEEL SENSOR REMOVAL
(1) On XJ models, raise and fold rear seat forward
for access to rear sensor connectors (Fig. 9).
(2) Disconnect sensors at rear harness connectors.
(3) Push sensor grommets and sensor wires
through floorpan.
(4) Raise vehicle.
(5) Disconnect sensor wires at rear axle connectors.
(6) Remove wheel and tire assembly.
(7) Remove brake drum.
(8) Remove clips securing sensor wires to brake-
lines, rear axle and, brake hose.
(9) Unseat sensor wire support plate grommet.
(10) Remove bolt attaching sensor to bracket and
remove sensor.
REAR WHEEL SENSOR INSTALLATION AND
ADJUSTMENT
(1) Iforiginal sensoris being installed, remove
any remaining pieces of cardboard spacer from sen-
sor pickup face. Use dry shop towel only to remove
old spacer material.
(2) Insert sensor wire through support plate hole.
Then seat sensor grommet in support plate.
(3) Apply Mopar Lock N' Seal or Loctite 242 to
Fig. 9 Acceleration Switch And Rear Sensor
Connections (XJ)
5 - 38 ABS OPERATION AND SERVICEJ

original sensor bolt. Use new bolt if original is worn
or damaged.
(4) Install sensor bolt finger tight only at this time.
(5) Iforiginalrear sensor was installed, adjust
sensor air gap to 0.92-1.45 mm (0.036-0.057 in.). Use
feeler gauge to measure air gap (Fig. 10). Tighten
sensor bolt to 11 Nzm (11 ft. lbs.) torque.
(6) Ifnewsensor was installed, push cardboard
spacer on sensor face against tone ring (Fig. 11).
Then tighten sensor bolt to 8 Nzm (6 ft. lbs.) torque.
Correct air gap will be established as tone ring ro-
tates and peels spacer off sensor face.
(7) On YJ, connect rear sensor wires to connectors
at axle. On XJ, route sensor wires to rear seat area.
(8) Feed sensor wires through floorpan access hole
and seat sensor grommets in floorpan.
(9) Verify that rear sensor wires are secured to
rear brake hose and axle with clips. Verify that wire
is clear of rotating components.
(10) Install brake drum and wheel.
(11) Lower vehicle.
(12) On XJ, connect sensor wire to harness connec-
tor. Then reposition carpet and fold rear seat down.
ACCELERATION SWITCH REMOVAL
(1) On XJ models, tilt rear seat assembly forward
for access to sensor (Fig. 12).(2) On YJ models, move driver seat forward or
rearward for access to sensor and mounting bracket
(Fig. 12).
(3) Disconnect switch harness.
(4) On XJ models, remove screws attaching switch
to bracket. Then remove switch.
(5) On YJ models, remove screws attaching switch
bracket to floorpan. Then remove switch from
bracket.
ACCELERATION SWITCH INSTALLATION
(1) Note position of locating arrow on switch.
Switch must be positioned so arrow faces forward.
Fig. 10 Setting Air Gap On Original Rear Sensor
Fig. 11 Location Of Spacer On New Rear Sensor
Fig. 12 Acceleration Switch Mounting (XJ/YJ)
JABS OPERATION AND SERVICE 5 - 39