washer fluid JEEP CHEROKEE 1995 Service Repair Manual

MAINTENANCE SCHEDULES
INTRODUCTION
There are two maintenance schedules that show
proper service intervals for Jeep Cherokee and Jeep
Wrangler vehicles. Use the schedule that best de-
scribes the conditions the vehicle is operated under.
When mileage and time is listed, follow the interval
that occurs first.
ScheduleÐAlists all the scheduled maintenance
to be performed under normal operating conditions.
ScheduleÐBis a schedule for vehicles that are
usually operated under one or more of the following
conditions.
²Frequent short trip driving less than 5 miles (8
km).
²Frequent driving in dusty conditions.
²Trailer towing or heavy load hauling.
²Frequent long periods of engine idling.
²Sustained high speed operation.
²Desert operation.
²Frequent starting and stopping.
²Cold climate operation.
²Off road driving.
²Commercial service.
²Snow plow operation.
²More than half of vehicle operation occurs in
heavy city traffic during hot weather (above 90É F).
AT EACH STOP FOR GASOLINE
²Check engine oil level and add as required.
²Check windshield washer solvent and add as re-
quired.
ONCE A MONTH
²Check tire pressure and look for unusual tire wear
or damage.
²Check fluid levels of coolant reservoir, brake mas-
ter cylinder, power steering and transmission. Add
fluid as required.
²Check all lights and other electrical items for cor-
rect operation.
²Inspect battery and clean and tighten terminals as
required.
²Check rubber seals on each side of the radiator for
proper fit.
AT EACH OIL CHANGE
²Inspect exhaust system.
²Inspect brake hoses.
²Rotate the tires at each oil change interval shown
on ScheduleÐA: (7,500 Miles) or every other interval
shown on ScheduleÐB: (6,000 Miles).
²Check engine coolant level, hoses, and clamps.
²Lubricate 4x4 steering linkage.
²Lubricate propeller shaft universal joints and slip
spline, if equipped.After completion of off-road (4WD) operation, the
underside of the vehicle should be thoroughly in-
spected. Examine threaded fasteners for looseness.
HARSH SURFACE ENVIRONMENTS
After vehicle operation in a harsh surface environ-
ment, the following components should be inspected
and cleaned as soon as possible:
²Brake drums.
²Brake linings.
²Front wheel bearings (2WD vehicles only).
²Axle coupling joints.
This will prevent wear and/or unpredictable brake
action.
EMISSION CONTROL SYSTEM MAINTENANCE
The schedule emission maintenance listed inbold
typeon the following schedules, must be done at the
mileage specified to assure the continued proper
functioning of the emission control system. These,
and all other maintenance services included in this
manual, should be done to provide the best vehicle
performance and reliability. More frequent mainte-
nance may be needed for vehicles in severe operating
conditions such as dusty areas and very short trip
driving.
SCHEDULEÐA
7,500 MILES (12 000 KM) OR AT 6 MONTHS
²Change engine oil.
²Replace engine oil filter.
²Lubricate steering linkage (4x4).
15,000 MILES (24 000 KM) OR AT 12 MONTHS
²Change engine oil.
²Replace engine oil filter.
²Lubricate steering linkage.
22,500 MILES (36 000 KM) OR AT 18 MONTHS
²Change engine oil.
²Replace engine oil filter.
²Lubricate steering linkage (4x4).
²Inspect brake linings.
30,000 MILES (48 000 KM) OR AT 24 MONTHS
²Replace air cleaner element.
²Replace spark plugs.
²Adjust belt tension on non-automatic tensioning
drive belts.
²Change engine oil.
²Replace engine oil filter.
²Lubricate steering linkage.
²Drain and refill automatic transmission.
²Drain and refill transfer case.
0 - 4 LUBRICATION AND MAINTENANCEJ

hose unless the caliper must also be removed
for maintenance.Support the caliper with a
hanger to prevent brake fluid hose damage.
(2) Remove the dust cap, the cotter pin, the nut re-
tainer, the adjustment nut, and the thrust washer
from the spindle (Fig. 3). Discard the cotter pin.
(3) Remove the wheel outer bearing from the hub.
(4) Remove the wheel hub/disc brake rotor from
the spindle.
(5) Remove the seal and the inner wheel bearing
from the hub cavity.
(6) After removal, inspect both front wheel bearing
races for indications of pitting, brinelling and exces-
sive heat.
(7) Wipe the spindle clean and apply a small
amount of chassis/wheel bearing lubricant (NLGI
GC-LB lubricant) to prevent rust. Wipe the wheel
hub cavity clean.
CAUTION: Do not over-fill the wheel hub cavity with
lubricant. Excessive lubricant can cause overheat-
ing and bearing damage. Also, excessive lubricant
can be forced out of the wheel hub cavity and con-
taminate the brake rotor/pads.
(8) Partially fill the wheel hub cavity with chassis/
wheel bearing lubricant (NLGI GC-LB lubricant).
(9) Pack the wheel bearings with chassis/wheel
bearing lubricant (NLGI GC-LB lubricant). Ensure
that sufficient lubricant is forced between the bear-
ing rollers.
(10) Install the wheel inner bearing in the wheel
hub and install a replacement seal.
(11) Clean the disc brake rotor contact surfaces, if
necessary.
(12) Install the wheel hub/disc brake rotor on the
spindle.
(13) Install the wheel outer bearing, the thrust
washer, and the spindle nut.(14) Tighten the spindle nut with 28 Nzm (21 ft.
lbs.) torque while rotating the disc brake rotor to
seat the bearings.
(15) Loosen the spindle nut 1/2 turn. While rotat-
ing the disc brake rotor, tighten the spindle nut with
2Nzm (19 in. lbs.) torque.
(16) Install the nut retainer and a replacement cot-
ter pin.
(17) Clean the dust cap and apply wheel bearing
lubricant to the inside surface.Do not fill the dust
cap with lubricant.
(18) Install the dust cap.
(19) Install the disc brake caliper.
POWER STEERING SYSTEM
The power steering fluid level should be inspected
when other under hood service is performed. For
proper service procedures, refer to Group 19, Steer-
ing.
Inspect the power steering system (Fig. 4, and 5)
for the sources of fluid leaks, steering gear housing
cracks and ensure that the steering gear is securely
attached to the vehicle frame rail. Inspect the steer-
ing damper for leaks and loose connections.
FLUID SPECIFICATION
Use MOPAR Power Steering Fluid, or an equiva-
lent product.
POWER STEERING FLUID INSPECTION
WARNING: ENGINE MUST NOT BE RUNNING WHEN
INSPECTING POWER STEERING FLUID LEVEL,
PERSONAL INJURY CAN RESULT.
Fig. 3 2WD Front Wheel BearingsÐXJ Vehicles
Fig. 4 Power Steering SystemÐXJ Vehicles
JLUBRICATION AND MAINTENANCE 0 - 29

(10) Inspect the roller bearing contact surface on
the axle shaft for signs of brinelling, spalling and pit-
ting.
(11) If any of these conditions exist, the axle shaft
and bearing or seal must be replaced.
INSTALLATION
(1) Lubricate the bearing bore and seal lip with
gear lubricant. Insert the axle shaft through the seal,
bearing, and engage it with the side gear splines.
Use care to prevent the shaft splines from dam-
aging the axle shaft seal lip.
(2) Insert the C-clip lock in the end of the axle
shaft. Push the axle shaft outward to seat the C-clip
lock in the side gear.
(3) Insert the mate shaft into the case and through
the thrust washers and pinion gears. Align the hole
in shaft with the hole in the differential case and in-
stall the lock screw with Loctiteton the threads.
Tighten the screw to 19 Nzm (14 ft. lbs.) torque.
(4) Install the cover and add fluid. Refer to the
Drain and Refill in this section.
AXLE SHAFT SEAL AND BEARING
REMOVAL
(1) Remove the axle shaft. Refer to the Removal
procedures in this Group.
(2) Remove the axle shaft seal from the end of the
axle shaft tube with a small pry bar.
(3) Remove the bearing if it appears damaged.
The seal and bearing can be removed at the same
time with the bearing removal tool.
(4) Remove the axle shaft bearing from the tube
(Fig. 8) with Bearing Removal Tool Set 6310 (T.Ar
960-02).
(5) Inspect the axle shaft tube bore for roughness
and burrs. Remove as necessary.
CAUTION: Inspect the housing bore for burrs. Re-
move them if they exist.
INSTALLATION
Do not install the original axle shaft seal. Al-
ways install a new seal.
(1) Wipe the bore in the axle shaft tube clean.
(2) Install axle shaft bearing with Installer 6436
and Handle C-4171. Ensure part number on the
bearing must go against the Installer.
(3) Install the new axle shaft seal (Fig. 9) with In-
staller 6437 and Handle C-4171.
(4) Install the Axle Shaft. Refer to the installation
procedure.
Fig. 6 Mate Shaft Lock Screw
Fig. 7 Axle Shaft C-Clip Lock
Fig. 8 Axle Shaft Bearing Removal Tool
JREAR SUSPENSION AND AXLES 3 - 17

(6) If removed, heat ring gear with a heat lamp or
by immersing in a hot fluid. The temperature should
not exceed 149ÉC (300ÉF).Do not use a torch to
heat the ring gear.
(7) Position heated rear gear on case. Use two
equally spaced Pilot Studs C-3288-B to align the gear
with the flange holes (Fig. 18).
(8) Install replacement ring gear bolts (with left
hand threads). Alternately and evenly tighten each
bolt to 95 Nzm (70 ft. lbs.) torque.
CAUTION: When installing a differential bearing,
never apply force to the bearing cage because bear-
ing damage will result.
(9) Install a differential bearing on each hub with
Installer C-4340 and Handle C-4171 (Fig. 19).PINION DEPTH MEASUREMENT AND
ADJUSTMENT WITH GAUGE SET 6575
(1) Use pinion gear adjustment gauge set 6575
(Fig. 20) and continue the assembly:
(2) Install front (outer) bearing cup use Installer
D-130 and Handle C-4171.
(3) Install rear (inner) bearing cup use Installer
C-4308 and Handle C-4171.
Assemble tools as described;
²Position Spacer (SP-6030) over Shaft (SP-5385)
²Position pinion rear bearing on shaft
²Position tools (with bearing) in the housing
²Install Sleeve (SP-5382)
²Install pinion front bearing
²Install Spacer (SP-6022)
²Install Sleeve (SP-3194-B), Washer (SP-534) and
Nut (SP-3193)
(4) Prevent compression sleeve tool from turning
with Wrench C-3281.
Tighten the nut to seat the pinion bearings in the
housing (Fig. 21). Allow the sleeve to turn several
times during the tightening to prevent brinelling the
bearing cups or bearings.
Depth shim(s) are positioned between the pin-
ion gear rear bearing and pinion gear. The re-
quired thickness of the depth shim(s) is
determined according to the following informa-
tion.
(5) Loosen the compression nut tool. Lubricate the
pinion gear front and rear bearings with gear lubri-
cant. Re-tighten the compression nut tool to 1 to 3
Nzm (15 to 25 in. lbs.) torque. Rotate the pinion gear
several complete revolutions to align the bearing roll-
ers.
(6) Install Gauge Block SP-5383 at the end of SP-
5385. Install Cap Screw (SP-536) and tighten.
(7) Position Arbor (SP-6029) in the differential
housing (Fig. 22).
Fig. 18 Case-To-Ring Gear Alignment
Fig. 19 Differential Bearing Installation
Fig. 20 Axle Adjustment ToolsÐ8 1/4
3 - 38 REAR SUSPENSION AND AXLESJ

If inspection or diagnosis indicates additional fluid
may be needed, use Mopar brake fluid, or an equiv-
alent meeting standards SAE J1703 and DOT 3. Do
not use any other type of fluid.
Clutch fluid level is checked at the master cylinder
reservoir (Fig. 13). An indicator ring is provided ei-
ther on the side, or interior rim of the reservoir (Fig.
14).
Be sure to wipe the reservoir and cover clean be-
fore removing the cover. This will avoid having dirt
or foreign material fall into the reservoir during a
fluid level check.
CLUTCH PEDAL REMOVAL
(1) Remove instrument panel lower trim cover for
extra working clearance.(2) Disconnect clutch pedal position switch wires.
(3) Remove retainer clip that attaches clutch mas-
ter cylinder push rod to pedal.
(4) On YJ, remove retaining ring securing pedal to
pivot shaft (Fig. 15). On XJ, remove nut securing
pedal to pivot shaft (Fig. 16).
(5) Move pedal pivot shaft to right and slide pedal
off shaft.
CLUTCH PEDAL INSTALLATION
(1) Lubricate clutch pedal pivot shaft and pedal
bushings or sleeve with Mopar multi-mileage grease.
(2) Position pedal on pivot shaft and through
brace. Secure pedal with washer and retaining ring
on YJ, or with washer and nut on XJ.
Fig. 13 Clutch Master Cylinder Reservoir And CapFig. 14 Reservoir Fluid Level Indicator Ring
Fig. 15 Clutch Pedal Mounting (YJ)
JCLUTCH SERVICE 6 - 15

On the 4.0L 6-cylinder engine, the ignition coil is
mounted to a bracket on the side of the engine (to
the front of the distributor) (Fig. 11).
For component testing, refer to the Diagnostics/Ser-
vice Procedures section of this group.
For removal and installation of this component, re-
fer to the Component Removal/Installation section of
this group.
ENGINE COOLANT TEMPERATURE SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
INTAKE MANIFOLD AIR TEMPERATURE SENSOR
For an operational description, diagnosis or remov-
al/ installation procedures, refer to Group 14, Fuel
Systems.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
POWERTRAIN CONTROL MODULE (PCM)
The PCM was formerly referred to as the SBEC or
engine controller. On XJ models, the PCM is located
in the engine compartment next to the air cleaner
(Fig. 12). On YJ models, the PCM is located in the
engine compartment behind the windshield washer
fluid reservoir (Fig. 13).
The ignition system is controlled by the PCM.
Base ignition timing by rotation of distributor
is not adjustable.The PCM opens and closes the ig-
nition coil ground circuit to operate the ignition coil.
This is done to adjust ignition timing, both initial
(base) and advance, for changing engine operating
conditions.The amount of electronic spark advance provided
by the PCM is determined by five input factors: En-
gine coolant temperature, engine rpm, intake mani-
fold air temperature, intake manifold absolute
pressure and throttle position.
For removal and installation of this component, re-
fer to the Component Removal/Installation section of
this group.
For PCM diagnostics, refer to the appropriate Pow-
ertrain Diagnostic Procedures service manual for op-
eration of the DRB scan tool.
THROTTLE POSITION SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
OXYGEN (O2S) SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
Fig. 11 Ignition CoilÐTypical
Fig. 12 PCM LocationÐXJ Models
Fig. 13 PCM LocationÐYJ Models
JIGNITION SYSTEMS 8D - 5

(4) Crank the engine for 5 seconds while monitor-
ing the voltage at the coil positive terminal:
²If the voltage remains near zero during the entire
period of cranking, refer to On-Board Diagnostics in
Group 14, Fuel Systems. Check the powertrain con-
trol module (PCM) and auto shutdown relay.
²If voltage is at or near battery voltage and drops
to zero after 1-2 seconds of cranking, check the cam-
shaft position sensor-to-PCM circuit. Refer to On-
Board Diagnostics in Group 14, Fuel Systems.
²If voltage remains at or near battery voltage dur-
ing the entire 5 seconds, turn the key off. Remove
the 60-way connector (Fig. 15) from the PCM. Check
60-way connector for any spread terminals.
(5) Remove test lead from the coil positive termi-
nal. Connect an 18 gauge jumper wire between the
battery positive terminal and the coil positive termi-
nal.
(6) Make the special jumper shown in figure 16.
Using the jumper,momentarilyground pin/cavity
number 19 of the PCM 60-way connector. A spark
should be generated at the coil cable when the
ground is removed.
(7) If spark is generated, replace the powertrain
control module (PCM).
(8) If spark is not seen, use the special jumper to
ground the coil negative terminal directly.
(9) If spark is produced, repair wiring harness for
an open condition.
(10) If spark is not produced, replace the ignition
coil.IGNITION TIMING
Base (initial) ignition timing is NOT adjust-
able on any of the 2.5L 4-cylinder or 4.0L 6-cyl-
inder engines. Do not attempt to adjust ignition
timing by rotating the distributor.
Do not attempt to modify the distributor
housing to get distributor rotation. Distributor
position will have no effect on ignition timing.
All ignition timing functions are controlled by the
powertrain control module (PCM). Refer to On-Board
Diagnostics in the Multi-Port Fuel InjectionÐGen-
eral Diagnosis section of Group 14, Fuel Systems for
more information. Also refer to the appropriate Pow-
ertrain Diagnostics Procedures service manual for op-
eration of the DRB Scan Tool.
INTAKE MANIFOLD AIR TEMPERATURE SENSOR
TEST
For an operational description, diagnosis or remov-
al/ installation procedures, refer to Group 14, Fuel
Systems.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
POWERTRAIN CONTROL MODULE (PCM)
The PCM (formerly referred to as the SBEC or en-
gine controller) is located in the engine compartment
behind the windshield washer fluid tank on YJ mod-
els (Fig. 17). It is located in the engine compartment
next to the air cleaner on XJ models (Fig. 18).
The ignition system is controlled by the PCM.
For removal and installation of this component, re-
fer to the Component Removal/Installation section of
this group.
Fig. 15 PCM 60-Way Connector
Fig. 16 Special Jumper Ground-to-Coil Negative
Terminal
Fig. 17 PCM LocationÐYJ Models
JIGNITION SYSTEMS 8D - 11

(3) Remove ignition coil mounting bolts (nuts are
used on back side of bracket). Remove coil.
INSTALLATION
(1) Install ignition coil to bracket on cylinder block
with mounting bolts and nuts.
(2) Connect engine harness connector to coil.
(3) Connect ignition coil cable to ignition coil.
INTAKE MANIFOLD AIR TEMPERATURE SENSOR
For an operational description, diagnosis or remov-
al/ installation procedures, refer to Group 14, Fuel
Systems.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
OXYGEN (O2S) SENSOR
For an operational description, diagnosis or remov-
al/ installation procedures, refer to Group 14, Fuel
Systems.
POWERTRAIN CONTROL MODULE (PCM)
The PCM was formerly referred to as the SBEC or
engine controller.
XJ MODELS
On XJ models, the PCM is located in the engine
compartment next to the air cleaner (Fig. 17).
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Loosen 60-way connector mounting screw until
connector can be disengaged from PCM.
(3) Pull 60-way connector straight back from PCM.
(4) Remove PCM mounting bolts.
(5) Remove PCM from vehicle.INSTALLATION
(1) Check the pins in the PCM 60-way electrical
connector for damage. Repair as necessary.
(2) Install PCM. Tighten mounting bolts to 1 Nzm
(9 in. lbs.) torque.
(3) Engage 60-way connector into PCM. Tighten
connector mounting screw to 4 Nzm (35 in. lbs.)
torque.
(4) Connect battery cable to battery.
YJ MODELS
On YJ models, the PCM is located in the engine
compartment behind the windshield washer fluid res-
ervoir (Fig. 18).
REMOVAL
(1) Disconnect negative battery cable at battery.
(2) Remove windshield washer fluid reservoir.
(3) Loosen 60-way connector mounting screw until
connector can be disengaged from PCM.
(4) Pull 60-way connector straight back from PCM.
(5) Remove PCM mounting bolts.
(6) Remove PCM from vehicle.
INSTALLATION
(1) Check the pins in the PCM 60-way electrical
connector for damage. Repair as necessary.
(2) Install PCM. Tighten mounting bolts to 1 Nzm
(9 in. lbs.) torque.
(3) Engage 60-way connector into PCM. Tighten
connector mounting screw to 4 Nzm (35 in. lbs.)
torque.
(4) Connect battery cable to battery.
(5) Install washer fluid reservoir.
SPARK PLUGS
PLUG REMOVAL
(1) Always remove spark plug or ignition coil ca-
bles by grasping at the cable boot (Fig. 19). Turn the
cable boot 1/2 turn and pull straight back in a steady
Fig. 17 PCM LocationÐXJ Models
Fig. 18 PCM LocationÐYJ Models
JIGNITION SYSTEMS 8D - 23

INSTRUMENT PANEL AND GAUGES
GROUP INDEX
INSTRUMENT PANEL AND GAUGESÐXJ...... 1INSTRUMENT PANEL AND GAUGESÐYJ..... 24
INSTRUMENT PANEL AND GAUGESÐXJ
CONTENTS
page page
DIAGNOSIS............................. 5
GENERAL INFORMATION.................. 1SERVICE PROCEDURES.................. 17
SPECIFICATIONS........................ 23
GENERAL INFORMATION
Following are general descriptions of major instru-
ment panel components. Refer to Group 8W - Wiring
Diagrams for complete circuit descriptions and dia-
grams.
INSTRUMENT PANEL
Modular instrument panel construction allows all
gauges and controls to be serviced from the front of
the panel. In addition, most instrument panel wiring
or heater and air conditioning components can be ac-
cessed without complete instrument panel removal. If
necessary, the instrument panel can be rolled-down
and removed from the vehicle as an assembly.
Removal of the instrument cluster bezel allows ac-
cess to the cluster assembly, most switches, the cli-
mate controls, and the radio. Removal of the cluster
assembly allows access to the individual gauges, illu-
mination and indicator lamp bulbs, printed circuits,
and most wiring.
Removal of the lower instrument panel allows ac-
cess to heater and air conditioning components, the
fuseblock module, the relay center, and other wiring
and electrical components. Those models equipped
with a driver's-side airbag restraint have a knee
blocker and reinforcement behind the driver's-side
lower instrument panel.
The instrument panel layout is mirror image for
left-hand and right-hand drive vehicles. In most
cases, the diagnosis and service procedures found in
this group are applicable to either vehicle. Although,most illustrations represent only the typical left-hand
drive version. Exceptions are clearly identified as
Right-Hand Drive (RHD).
INSTRUMENT CLUSTERS
Two basic instrument cluster options are offered on
XJ (Cherokee) models. One is referred to as a low-
line cluster, and the other is referred to as a high-
line cluster. Each cluster is divided into two areas:
the gauge area, and the tell-tale area. Each area is
served by a separate printed circuit and wiring con-
nector. Some variations of each cluster exist due to
optional equipment and regulatory requirements.
The low-line cluster includes the following gauges:
²fuel gauge
²speedometer/odometer.
The low-line cluster includes provisions for the fol-
lowing indicator lamps:
²anti-lock brake system lamp
²brake warning lamp
²coolant temperature warning lamp
²four-wheel drive indicator lamps
²generator warning lamp
²headlamp high beam indicator lamp
²low oil pressure warning lamp
²low washer fluid warning lamp
²malfunction indicator (Check Engine) lamp
²seat belt reminder lamp
²turn signal indicator lamps
²upshift indicator lamp.
JINSTRUMENT PANEL AND GAUGES 8E - 1

The high-line cluster includes the following gauges:
²coolant temperature gauge
²fuel gauge
²oil pressure gauge
²speedometer/odometer
²tachometer
²trip odometer
²voltmeter.
The high-line cluster includes provisions for the fol-
lowing indicator lamps:
²anti-lock brake system lamp
²brake warning lamp
²four-wheel drive indicator lamps
²headlamp high beam indicator lamp
²low fuel warning lamp
²low washer fluid warning lamp
²malfunction indicator (Check Engine) lamp
²seat belt reminder lamp
²turn signal indicator lamps
²upshift indicator lamp.
GAUGES
With the ignition switch in the ON or START posi-
tion, voltage is supplied to all gauges through the in-
strument cluster gauge area printed circuit. With the
ignition switch in the OFF position, voltage is not
supplied to the gauges. A gauge pointer may remain
within the gauge scale after the ignition switch is
OFF. However, the gauges do not accurately indicate
any vehicle condition unless the ignition switch is
ON.
All gauges except the odometer are air core mag-
netic units. Two fixed electromagnetic coils are lo-
cated within the gauge. These coils are wrapped at
right angles to each other around a movable perma-
nent magnet. The movable magnet is suspended
within the coils on one end of a shaft. The gauge nee-
dle is attached to the other end of the shaft.
One of the coils has a fixed current flowing through
it to maintain a constant magnetic field strength.
Current flow through the second coil changes, which
causes changes in its magnetic field strength. The
current flowing through the second coil can be
changed by:
²a variable resistor-type sending unit (fuel level,
coolant temperature, or oil pressure)
²changes in electrical system voltage (voltmeter)
²electronic control circuitry (speedometer/odometer,
tachometer).
The gauge needle moves as the movable permanent
magnet aligns itself to the changing magnetic fields
created around it by the electromagnets.
COOLANT TEMPERATURE GAUGE
The coolant temperature gauge gives an indication
of engine coolant temperature. The coolant tempera-
ture sending unit is a thermistor that changes elec-
trical resistance with changes in engine coolanttemperature. High sending unit resistance causes
low coolant temperature readings. Low resistance
causes high coolant temperature readings.
The gauge will read at the high end of the scale
when the ignition switch is turned to the START po-
sition. This is caused by the bulb test circuit wiring
provision. The same wiring is used for the high-line
cluster with a coolant temperature gauge and the
low-line cluster with a coolant temperature warning
lamp. Sending unit resistance values are shown in a
chart in Specifications.
FUEL GAUGE
The fuel gauge gives an indication of the level of
fuel in the fuel tank. The fuel gauge sending unit has
a float attached to a swing-arm in the fuel tank. The
float moves up or down within the fuel tank as fuel
level changes. As the float moves, an electrical con-
tact on the swing-arm wipes across a resistor coil,
which changes sending unit resistance. High sending
unit resistance causes low fuel level readings. Low
resistance causes high fuel level readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
OIL PRESSURE GAUGE
The oil pressure gauge gives an indication of en-
gine oil pressure. The combination oil pressure send-
ing unit contains a flexible diaphragm. The
diaphragm moves in response to changes in engine
oil pressure. As the diaphragm moves, sending unit
resistance increases or decreases. High resistance on
the gauge side of the sending unit causes high oil
pressure readings. Low resistance causes low oil
pressure readings. Sending unit resistance values are
shown in a chart in Specifications.
SPEEDOMETER/ODOMETER
The speedometer/odometer gives an indication of
vehicle speed and travel distance. The speedometer
receives a vehicle speed pulse signal from the Vehicle
Speed Sensor (VSS). An electronic integrated circuit
contained within the speedometer reads and analyzes
the pulse signal. It then adjusts the ground path re-
sistance of one electromagnet in the gauge to control
needle movement. It also sends signals to an electric
stepper motor to control movement of the odometer
number rolls. Frequency values for the pulse signal
are shown in a chart in Specifications.
The VSS is mounted to an adapter near the trans-
mission (two-wheel drive) or transfer case (four-wheel
drive) output shaft. The sensor is driven through the
adapter by a speedometer pinion gear. The adapter
and pinion vary with transmission, transfer case,
axle ratio and tire size. Refer to Group 21 - Trans-
mission and Transfer Case for more information.
8E - 2 INSTRUMENT PANEL AND GAUGESÐXJJ