1994 JEEP CHEROKEE length

(7) Apply a small amount of chassis lubricant (or
an equivalent protective coating) to the cable termi-
nals to minimize corrosion.
RUBBER AND PLASTIC DUCTS/HOSES/TUBING
RECOMMENDED MAINTENANCE
Rubber and plastic ducts/hoses/tubing should be in-
spected at the same time the engine oil is changed
and the oil filter is replaced.
The conditions associated with vehicle operation
determines the usable life of the rubber and plastic
ducts/hoses/tubing. These conditions include:
²the extent and quality of vehicle maintenance,
²the geographic area of vehicle operation, and
²the length of exposure time to excess heat and
chemical contaminants.
DUCT/HOSE/TUBING INSPECTIONÐEXCEPT
EMISSION CONTROL HOSES/TUBING
Refer to Group 25ÐEmission Control Systems.
Engine performance could be affected by air leaks
into various hoses.
Rubber/plastic ducts, hoses and tubing should
be replaced immediately if there is any evidence
of deterioration.
(1) Inspect all hose fittings for looseness and corro-
sion. Inspect rubber ducts (Fig. 12) and hoses for
brittleness and cracks. Examine the hose ends (those
that are slipped over nipple connectors) for splits.
(2) Inspect surface of hoses and tubing (Fig. 13) for
heat and mechanical damage.The hose and tubing
that is located near an exhaust manifold should
be given special attention.
(3) Inspect the rubber hose routing to ensure that
the hoses do not contact any heat source, moving
component, etc., that could potentially cause heat or
mechanical damage (Figs. 14, 15, and 16).
(4) Inspect all the hose connections to ensure that
they are secure and that there is no fluid leakage. Inmany instances, liquid lubricants are used to aid in
the connection of hoses to couplings.
Fig. 12 Intake Air Duct (XJ)ÐTypical
Fig. 13 Washer Fluid TubingÐTypical
Fig. 14 ATF Cooler Hoses ÐXJ Vehicles
Fig. 11 Brake Booster Vacuum Hose (XJ)ÐTypical
JLUBRICATION AND MAINTENANCE 0 - 19

DRIVETRAIN
INDEX
page page
Automatic Transmission.................... 23
Drive Shafts............................ 27
Front and Rear Axles..................... 26
Hydraulic Clutch......................... 22Manual Transmission...................... 22
Rubber and Plastic Hoses/Tubing............ 28
Transfer Case........................... 25
HYDRAULIC CLUTCH
RECOMMENDED MAINTENANCE
Check fluid level in the hydraulic clutch master
cylinder reservoir (Fig. 1) at the same time engine
oil is changed and oil filter is replaced. Add fluid as
necessary.
FLUID SPECIFICATION
The only fluid recommended for use in a hydraulic
clutch system is MOPAR Brake And Hydraulic
Clutch Fluid., or an equivalent fluid.
CAUTION: Never use reclaimed brake fluid or fluid
from an unsealed container. In addition, do not use
fluid from a container that has been opened and al-
lowed to stand for an extended length of time.
Moisture in the air can be absorbed by the fluid,
which causes dilution with loss of effectiveness.
FLUID LEVEL
Remove the master cylinder fluid reservoir cap
(Fig. 2). The fluid level is determined by its height inrelation to the level indicator ring (Fig. 3) located in-
side the reservoir. If necessary, add fluid until the
height is level with the indicator ring.
MANUAL TRANSMISSION
RECOMMENDED MAINTENANCE
The lube oil level in manual transmissions should
be determined at the same time as the engine oil is
changed and the oil filter is replaced. Add lube oil as
necessary.
Fig. 1 Hydraulic Clutch (YJ)ÐTypical
Fig. 2 Hydraulic Clutch Master Cylinder Fluid
Reservoir
Fig. 3 Hydraulic Clutch Fluid Level
0 - 22 LUBRICATION AND MAINTENANCEJ

CAUTION: It is very important that drive shafts be
lubricated at periodic intervals and that the speci-
fied type of lubricant be used. Failure to properly
lubricate could result in premature wear of drive
shaft components.
LUBRICATION FITTINGS
The drive shaft universal-joint couplers (U-joints)
and the front drive shaft slip yoke splines are
equipped with Zerk fittings. The (CV-joints) are lu-
bricated when assembled during manufacture and do
not require additional lubrication.
LUBRICANT SPECIFICATION
Drive shaft U-joint couplers and slip yoke splines
should be lubricated with a lubricant that is identi-
fied as NLGI GC-LB lubricant.
SLIP-YOKE SPLINE LUBRICATION
The method below will ensure complete lubrication
of the front drive shaft slip-yoke splines (Fig. 14).
(1) Clean the tips of the Zerk type fittings.
(2) Use a gun or another appropriate lubricant dis-
penser to force pressurized lubricant into the slip
yoke Zerk fittings.
(3) When the lubricant appears, cover the pressure
relief hole with a finger. Force pressurized lubricant
into fitting until it appears at slip-yoke seal.
RUBBER AND PLASTIC HOSES/TUBING
RECOMMENDED MAINTENANCE
The condition of underbody rubber hose and plastic
tubing should be inspected for failure at the same
time as oil is changed and oil filter is replaced.
HOSE/TUBING INSPECTION
Vehicle operating conditions determine the useable
life of underbody hoses and tubing. These conditions
include:²the extent and quality of vehicle maintenance,
²the geographic area of vehicle operation, and
²the length of exposure time to excess heat and
chemical contaminants.
(1) Inspect all hose and tubing fittings for loose-
ness and corrosion. Inspect the rubber hoses for brit-
tleness and cracks. Thoroughly inspect the hose ends
(those that are slipped over nipple connectors) for
splits (Figs. 16, 17, 18, 19, 20, 21 and 22).
Fig. 16 Front Axle Vent Hose (4WD)ÐXJ Vehicles
Fig. 17 Front Axle Vent HoseÐYJ Vehicles
Fig. 15 Rear Drive Shaft (4WD)ÐTypical
0 - 28 LUBRICATION AND MAINTENANCEJ

FRONT SUSPENSION AND AXLE
CONTENTS
page page
AXLE NOISE/VIBRATION DIAGNOSIS....... 16
FRONT WHEEL ALIGNMENT............... 5
GENERAL INFORMATION.................. 1
MODEL 30 AXLE AND TUBE AXLE (2WD) . . 20TORQUE SPECIFICATIONS................ 47
XJ FRONT SUSPENSION................. 10
YJ FRONT SUSPENSION................. 13
GENERAL INFORMATION
FRONT SUSPENSION
XJ VEHICLES
The Cherokee front suspension is a link/coil design
comprised of (Fig. 1);
²Drive axle (4WD), tube axle (2WD)
²Track bar
²Stabilizer bar
²Upper and lower suspension arms
²Coil springs
²Dual-action shock absorbers²Jounce bumpers (used to limit the travel of the
suspension)
The link/coil suspension allows each wheel to adapt
to different road surfaces without greatly affecting
the opposite wheel. Wheels are attached to a hub/
bearings which bolts to the knuckles. The hub/bear-
ing is not serviceable and is replaced as a unit.
Steering knuckles pivot on replaceable ball studs at-
tached to the axle tube yokes.
The upper and lower suspension arms are different
lengths, with bushings at both ends. They bolt the
Fig. 1 XJ Front Suspension
JFRONT SUSPENSION AND AXLE 2 - 1

axle assembly to the frame. The lower arms uses
shims at the frame mount to allow for adjustment of
caster and pinion angle. The suspension arm travel
(jounce or rebound) is limited through the use of rub-
ber bumpers.
Suspension components which use rubber bushings
should be tightened at vehicle ride height. This will
prevent premature failure of the bushing and main-
tain ride comfort. Bushings must never be lubricated.
The coil springs control ride quality and maintain
proper ride height. The coil springs mount up in the
fender shield which is part of the unitized body
bracket. A rubber isolator is located between the top
of the spring and the frame. The bottom of the spring
seats on a axle pad and is retained with a clip.
The shock absorbers dampen jounce and rebound of
the vehicle over various road conditions. The top of
the shock absorbers are bolted to the frame. The bot-
tom of the shocks are bolted to the axle spring
bracket.
The stabilizer bar is used to minimize vehicle front
sway during turns. The spring steel bar helps to con-
trol the vehicle body in relationship to the suspen-
sion. The bar extends across the front underside of
the chassis and connects to the frame rails. Links are
connected from the bar to the axle brackets. Stabi-
lizer bar mounts are isolated by rubber bushings.
The track bar is used to minimize front axle side-
to-side movement. The bar is attached to a frame rail
bracket with a ball stud and isolated with a bushing
at the axle bracket.
TUBE AXLE (2WD VEHICLES)
The front axle used on two-wheel drive vehicles is
a one-piece, tubular axle (Fig. 2). The tubular axle
mounts in the same bracketry as does the four-wheel
drive front axle. The steering knuckles and hub bear-
ing assemblies are the same as used on the Model 30
drive axle.
YJ VEHICLES
The Wrangler (YJ) front suspension is leaf spring
design comprised of (Fig. 3);
²Drive axle
²Track bar
²Stabilizer bar
²Leaf springs
²Dual-action shock absorbers
²Jounce bumpers (used to limit the travel of the
suspension)
The front suspension uses semi-elliptic multi-leaf
springs mounted on the drive axle. The rearward end
of the springs are mounted to the frame rail hangers
through rubber bushings. The bushings isolate road
noise as the springs move. The forward end of the
springs are attached to the frame with shackles. The
spring and shackles use rubber bushings to isolate
road noise. The shackles allow the springs to changetheir length as the vehicle moves over various road
conditions. The spring and axle travel (jounce or re-
bound) is limited through use of rubber bumpers
mounted on the frame.
Suspension components which use rubber bushings
should be tightened at vehicle ride height. This will
prevent premature failure of the bushing and main-
tain ride comfort. The bushings should never be lu-
bricated.
Fig. 2 Front AxleÐ 2WD Vehicles
Fig. 3 YJ Front Suspension
2 - 2 FRONT SUSPENSION AND AXLEJ

MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT DESCRIPTION/SYSTEM
OPERATION
INDEX
page page
Air Conditioning (A/C) Clutch RelayÐPCM Output.24
Air Conditioning (A/C) ControlsÐPCM Input.... 19
Auto Shut Down (ASD) RelayÐPCM Output.... 24
Automatic Shut Down (ASD) SenseÐPCM Input . 19
Battery VoltageÐPCM Input................ 19
Brake SwitchÐPCM Input.................. 20
Camshaft Position SensorÐPCM Input........ 20
Crankshaft Position SensorÐPCM Input....... 20
Data Link ConnectorÐPCM Input............ 20
Data Link ConnectorÐPCM Output........... 24
EMR LampÐPCM Output.................. 24
Engine Coolant Temperature SensorÐPCM Input . 21
Extended Idle SwitchÐPCM Input............ 21
Fuel InjectorsÐPCM Output................ 25
Fuel Pressure Regulator................... 30
Fuel Pump RelayÐPCM Output............. 25
Fuel Rail............................... 30
General Information....................... 17
Generator FieldÐPCM Output............... 25
Generator LampÐPCM Output.............. 25
Idle Air Control (IAC) MotorÐPCM Output...... 25
Ignition Circuit SenseÐPCM Input............ 21
Ignition CoilÐPCM Output.................. 26Intake Air Temperature SensorÐPCM Input.... 20
Malfunction Indicator LampÐPCM Output...... 26
Manifold Absolute Pressure (MAP) SensorÐ
PCM Input............................ 21
Open Loop/Closed Loop Modes of Operation . . . 27
Overdrive/Override Switch.................. 22
Oxygen (O2S) SensorÐPCM Input........... 22
Park/Neutral SwitchÐPCM Input............. 22
Power Ground........................... 22
Power Steering Pressure SwitchÐPCM Input . . . 22
Powertrain Control Module (PCM)............ 18
Radiator Fan RelayÐPCM Output............ 26
SCI ReceiveÐPCM Input.................. 22
SCI TransmitÐPCM Output................. 26
Sensor ReturnÐPCM Input................. 23
Shift IndicatorÐPCM Output................ 26
Speed ControlÐPCM Input................. 23
Speed ControlÐPCM Output................ 27
TachometerÐPCM Output.................. 27
Throttle Body............................ 29
Throttle Position Sensor (TPS)ÐPCM Input..... 23
Torque Converter Clutch RelayÐPCM Output . . . 27
Vehicle Speed SensorÐPCM Input........... 23
GENERAL INFORMATION
All 2.5L 4 cylinder and 4.0L 6 cylinder engines are
equipped with sequential Multi-Port Fuel Injection
(MFI). The MFI system provides precise air/fuel ra-
tios for all driving conditions.
The Powertrain Control Module (PCM) operates
the fuel system. The PCM was formerly referred to
as the SBEC or engine controller. The PCM is a pre-
programmed, dual microprocessor digital computer.
It regulates ignition timing, air-fuel ratio, emission
control devices, charging system, speed control, air
conditioning compressor clutch engagement and idle
speed. The PCM can adapt its programming to meet
changing operating conditions.
Powertrain Control Module (PCM) Inputsrep-
resent the instantaneous engine operating conditions.
Air-fuel mixture and ignition timing calibrations for
various driving and atmospheric conditions are pre-
programmed into the PCM. The PCM monitors and
analyzes various inputs. It then computes engine fuel
and ignition timing requirements based on these in-
puts. Fuel delivery control and ignition timing will
then be adjusted accordingly.
Other inputs to the PCM are provided by the brake
light switch, air conditioning select switch and the
speed control switches. All inputs to the PCM are
converted into signals.
Electrically operated fuel injectors spray fuel in
precise metered amounts into the intake port directlyabove the intake valve. The injectors are fired in a
specific sequence by the PCM. The PCM maintains
an air/fuel ratio of 14.7 to 1 by constantly adjusting
injector pulse width. Injector pulse width is the
length of time that the injector opens and sprays fuel
into the chamber. The PCM adjusts injector pulse
width by opening and closing the ground path to the
injector.
Manifold absolute pressure (air density) and engine
rpm (speed) are the primary inputs that determine
fuel injector pulse width. The PCM also monitors
other inputs when adjusting air-fuel ratio.
Inputs That Effect Fuel Injector Pulse Width
²Exhaust gas oxygen content
²Engine coolant temperature
²Manifold absolute pressure (MAP)
²Engine speed
²Throttle position
²Battery voltage
²Air conditioning selection
²Transmission gear selection (automatic transmis-
sions only)
²Speed control
The powertrain control module (PCM) adjusts igni-
tion timing by controlling ignition coil operation. The
ignition coil receives battery voltage when the igni-
tion key is in the run or starter position. The PCM
provides a ground for the ignition coil. The coil dis-
JFUEL SYSTEM 14 - 17

Brake drag also has a direct effect on fuel economy.
If undetected, minor brake drag can be misdiagnosed
as an engine or transmission/torque converter prob-
lem.
Minor drag will usually cause slight surface char-
ring of the lining. It can also generate hard spots in
rotors and drums from the overheat/cool down pro-
cess. In most cases, the rotors, drums, wheels and
tires are quite warm to the touch after the vehicle is
stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and
drums to the point of replacement. The wheels, tires
and brake components will be extremely hot. In se-
vere cases, the lining may generate smoke as it chars
from overheating.
An additional cause of drag involves the use of in-
correct length caliper mounting bolts. Bolts that are
too long can cause a partial apply condition. The cor-
rect caliper bolts have a shank length of 67 mm
(2.637 in.), plus or minus 0.6 mm (0.0236 in.). Refer
to the Disc Brake service section for more detail on
caliper bolt dimensions and identification.
Some common causes of brake drag are:
²loose or damaged wheel bearing
²seized or sticking caliper or wheel cylinder piston
²caliper binding on bushings or slide surfaces
²wrong length caliper mounting bolts (too long)
²loose caliper mounting bracket
²distorted brake drum or shoes
²rear brakeshoes binding on worn/damaged support
plates
²severely rusted/corroded components
²misassembled components.
If brake drag occurs at all wheels, the problem may
be related to a blocked master cylinder compensator
port or faulty power booster (binds-does not release).
The brakelight switch can also be a cause of drag.
An improperly mounted or adjusted brakelight
switch can prevent full brake pedal return. The re-
sult will be the same as if the master cylinder com-
pensator ports are blocked. The brakes would be
partially applied causing drag.
BRAKE FADE
Brake fade is a product of overheating caused by
brake drag. However, overheating and subsequent
fade can also be caused by riding the brake pedal,
making repeated high deceleration stops in a short
time span, or constant braking on steep roads. Refer
to the Brake Drag information in this section for
causes.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
Disc brake rotors with excessive lateral runout or
thickness variation, or out of round brake drums arethe primary causes of pulsation. Other causes are
loose wheel bearings or calipers and worn, damaged
tires.
PULL
A front pull condition could be the result of:
²contaminated lining in one caliper
²seized caliper piston
²binding caliper
²wrong caliper mounting bolts (too long)
²loose caliper
²loose or corroded mounting bolts
²improper brakeshoes
²damaged rotor
²incorrect wheel bearing adjustment (at one wheel)
A worn, damaged wheel bearing or suspension
component are further causes of pull. A damaged
front tire (bruised, ply separation) can also cause
pull. Wrong caliper bolts (too long) will cause a par-
tial apply condition and pull if only one caliper is in-
volved.
A common and frequently misdiagnosed pull condi-
tion is where direction of pull changes after a few
stops. The cause is a combination of brake drag fol-
lowed by fade at the dragging brake unit.
As the dragging brake overheats, efficiency is so
reduced that fade occurs. If the opposite brake unit is
still functioning normally, its braking effect is mag-
nified. This causes pull to switch direction in favor of
the brake unit that is functioning normally.
When diagnosing a change in pull condition, re-
member that pull will return to the original direction
if the dragging brake unit is allowed to cool down
(and is not seriously damaged).
REAR BRAKE GRAB
Rear grab (or pull) is usually caused by contami-
nated lining, bent or binding shoes and support
plates, or improperly assembled components. This is
particularly true when only one rear wheel is in-
volved. However, when both rear wheels are affected,
the master cylinder or proportioning valve could be
at fault.
BRAKES DO NOT HOLD AFTER DRIVING
THROUGH DEEP WATER PUDDLES
This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by
driving with the brakes lightly applied for a mile or
two. However, if the lining is both wet and dirty, dis-
assembly and cleaning will be necessary.
BRAKE FLUID CONTAMINATION
There are two basic causes of brake fluid contami-
nation. The first involves allowing dirt, debris, or
other liquid materials to enter the cylinder reservoirs
JBRAKES 5 - 9

POWER BOOSTER VACUUM TEST
(1) Connect a vacuum gauge to the booster check
valve with a short length of hose and T-fitting (Fig.
3).
(2) Start and run engine at idle speed for one
minute.
(3) Clamp hose shut between vacuum source and
check valve (Fig. 3).
(4) Stop engine and observe vacuum gauge.
(5) If vacuum drops more than one inch HG (33
millibars) within 15 seconds, booster diaphragm or
check valve is faulty.
Fig. 3 Booster Vacuum Test Connections
5 - 12 BRAKESJ