brake sensor JEEP CHEROKEE 1994 Service Owner's Manual

Clean the reservoir and caps thoroughly before
checking level or adding fluid. Cap open lines and
hoses during service to prevent dirt entry.
Dirt or foreign material entering the ABS hydrau-
lic system through the reservoir opening will circu-
late within the system. The result will be poor brake
performance and possible component failure. Use
clean, fresh fluid only to top off, or refill the system.
WHEEL SENSOR AIR GAP ADJUSTMENT
Only rear sensor air gap is adjustable. The front
sensors are fixed and cannot be adjusted.
A rear sensor air gap adjustment is only
needed when reinstalling an original sensor. Re-
placement sensors have an air gap spacer at-
tached to the sensor pickup face. The spacer
establishes correct air gap when pressed against
the tone ring during installation. As the tone
ring rotates, it peels the spacer off the sensor to
create the required air gap.
Preferred rear sensor air gap is 1.1 mm (0.043 in.).
Acceptable air gap range is 0.92 to 1.275 mm (0.036
to 0.050 in.).
Front sensor air gap is not adjustable. The front
sensors are fixed in position and cannot be adjusted.
Front sensor air gap can only be checked. Air gap
should be 0.040 to 1.3 mm (0.0157 to 0.051 in.). If
front sensor air gap is incorrect, the sensor is either
loose, or damaged.
FRONT WHEEL SENSOR REMOVAL
(1) Raise vehicle and turn wheel outward for eas-
ier access to sensor.
(2) Remove sensor wire from mounting brackets.
(3) Clean sensor and surrounding area before removal.
(4) Remove bolt attaching sensor to steering
knuckle and remove sensor.
(5) Unseat grommet retaining sensor wire in wheel
house panel.
(6) In engine compartment, disconnect sensor wire con-
nector at harness plug. Then remove sensor and wire.
FRONT WHEEL SENSOR INSTALLATION
(1) Apply Mopar Lock N' Seal or Loctite 242 to
bolt that attaches sensor to steering knuckle. Use
new sensor bolt if original bolt is worn or damaged.
(2) Position sensor on steering knuckle. Seat sen-
sor locating tab in hole in knuckle and install sensor
attaching bolt finger tight.
(3) Tighten sensor bolt to 14 NIm (11 ft. lbs.) torque.
(4) Attach sensor wire to steering knuckle bracket
with grommets on sensor wire.
(5) Route sensor wire forward and behind shock
absorber. Then attach sensor wire to spring seat
bracket with grommets on sensor wire.
(6) Route sensor wire to outer sill bracket. Remove
all twists or kinks from wire.(7) Attach sensor wire to sill bracket with grom-
met. Be sure wire is free of twists and kinks.
(8) 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.
(9) Seat sensor wire grommet in body panel and
clip wire to brake line at grommet location.
(10) Connect sensor wire to harness in engine com-
partment.
REAR WHEEL SENSOR REMOVAL
(1) On XJ models, if separate connectors are not
used to attach sensor harness to each sensor wire,
proceed as follows:
(a) Raise and fold rear seat forward for access to
rear sensor connectors (Figs. 4 and 5).
(b) Disconnect sensors at rear harness connectors.
(c) Push sensor grommets and sensor wires
through floorpan.
Fig. 4 Acceleration Switch And Rear Sensor
Connections (XJ)
Fig. 5 Rear Sensor Connections (XJ)
JABS COMPONENT SERVICE 5 - 49

(2) Raise vehicle.
(3) Disconnect sensor wires at rear axle connectors.
(4) Remove wheel and tire assembly.
(5) Remove brake drum.
(6) Remove clips securing sensor wires to brake
lines or rear axle and rear brake hose.
(7) Unseat sensor support plate grommet.
(8) Remove bolt attaching sensor to bracket and
remove sensor.
REAR WHEEL SENSOR INSTALLATION
(1) Insert sensor wire through support plate hole
and seat sensor grommet in support plate.
(2) Apply Mopar Lock N' Seal or Loctite 242 to
original sensor bolt. Use new bolt if original is worn
or damaged.
(3) Install sensor bolt finger tight only at this
time.
(4) Set sensor air gap as follows:
(a) Iforiginal sensoris being installed, remove
any remaining pieces of cardboard spacer from sen-
sor pickup face. Then adjust air gap to preferred
setting of 1.1 mm (0.043 in.) with brass feeler
gauge (Fig. 6). Tighten sensor bolt to 11 Nzm (11 ft.
lbs.) torque.
(b) Ifnew sensoris being installed, push card-
board spacer on sensor face (Fig. 7) against tone
ring. Then tighten sensor bolt to 8 Nzm (6 ft. lbs.)
torque. Correct air gap will be established as tone
ring rotates and peels spacer off sensor face.
(c) Verify sensor air gap adjustment. If adjust-
ment changed after tightening bolt, readjust sensor
air gap as needed.
(5) On YJ, connect rear sensor wires to connectors
at axle. On XJ, route sensor wires to rear seat area.
(6) Feed sensor wires through floorpan access hole
and seat sensor grommets in floorpan.
(7) Verify that rear sensor wire are secured to rear
brake hose and axle with clips. Verify that wire is
clear of rotating components.
(8) Install brake drum and wheel.
(9) Lower vehicle.
(10) On XJ, connect sensor wire to harness connec-
tor. Then reposition carpet and fold rear seat down.
MASTER CYLINDER REMOVAL
(1) Disconnect pedal travel sensor wires.
(2) Remove air cleaner and hoses on XJ models.
(3) Remove clamps that secure reservoir hoses to
HCU pipes.
(4) Position small drain container under master
cylinder reservoir. Remove reservoir hoses from HCU
pipes and allow fluid to drain into container before
removing reservoir. Discard fluid drained from reser-
voir.
(5) Pump brake pedal to exhaust all vacuum from
power brake booster.
(6) Disconnect necessary brakelines at master cyl-
inder and combination valve. Also remove combina-
tion valve bracket bolt.
(7) Remove nuts attaching master cylinder to
booster mounting studs.
(8) Remove master cylinder. Pull cylinder forward
and off studs. Then work cylinder past combination
valve, brakelines, pedal travel sensor and out of en-
gine compartment.
MASTER CYLINDER INSTALLATION
(1) If new master cylinder is being installed, bleed
cylinder on bench before installing it in vehicle.
(2) Work master cylinder into position and install
it in booster. Be sure cylinder is properly seated on
booster studs. Also be sure booster-to-cylinder seal is
not displaced during installation.
(3) Connect reservoir hoses to HCU pipes.
(4) Verify that master cylinder and booster are
properly connected.
(5) Install and tighten master cylinder attaching
nuts to 34 Nzm (25 ft. lbs.) torque.
(6) Connect brakelines to master cylinder.
(7) Install combination valve, if removed and in-
stall bolt that secures valve bracket to master cylin-
der.
(8) Connect sensor wires.
Fig. 6 Setting Air Gap On Original Rear Sensor
Fig. 7 New Rear Sensor With Air Gap Spacer
5 - 50 ABS COMPONENT SERVICEJ

(9) Fill reservoir and bleed brakes. Refer to proce-
dure in this section.
(10) Install air cleaner and hoses.
PEDAL TRAVEL SENSOR SERVICE
CAUTION: The pedal travel sensor and booster
must form a matched set. The cap on the sensor
plunger and booster shell are color coded for iden-
tification, and to ensure they are used as matched
sets. Be sure the color of the sensor cap and the
color dot on the booster shell are the same before
installation. Refer to the Sensor Replacement infor-
mation before installing a new or original sensor.
PEDAL TRAVEL SENSOR REMOVAL
(1) Disconnect wires at sensor.
(2) Pump brake pedal to exhaust all vacuum from
booster.
(3) Unseat sensor retaining ring.
(4) Remove sensor from booster (Fig. 8).
PEDAL TRAVEL SENSOR REPLACEMENT
A new pedal travel sensor is supplied with four dif-
ferent color caps. The caps are color coded to ease
matching them with the color code dot on the booster
shell.
Compare the color of the new sensor cap and the
color dot on the booster shell. If the colors match,
proceed with sensor installation. However, if the col-
orsdo not match, select and install the correct color
cap on the sensor plunger before proceeding.
PEDAL TRAVEL SENSOR INSTALLATION
(1) Check color dot on face of brake booster. Then
check color of cap on sensor plunger. If colors match,
proceed with installation. If colors do not match, in-
stall correct color cap on end of plunger.
(2) Install O-ring on sensor.
(3) Install sensor retaining ring on booster flange.
(4) Insert sensor in retaining ring and booster.
(5) Verify that retaining ring is properly engaged
in sensor and that sensor is seated in booster.
(6) Connect wires to sensor.
(7) Check sensor operation with DRB II scan tool.
POWER BRAKE BOOSTER REMOVAL
(1) Pump brake pedal until all vacuum is ex-
hausted from power brake booster.
(2) Disconnect pedal travel sensor.
(3) Remove air cleaner and hoses.
(4) Remove clamps that secure reservoir hoses to
HCU pipes. Then remove hoses from pipes.
(5) Disconnect brakelines at master cylinder.
(6) Remove combination valve bracket bolt if nec-
essary.
(7) Remove nuts attaching master cylinder to
booster mounting studs.(8) Remove master cylinder. Pull cylinder forward
and off studs. Then work cylinder past combination
valve, brakelines, pedal travel sensor and out of en-
gine compartment.
(9) Disconnect vacuum hose at booster check valve.
(10) Disconnect booster push rod from brake pedal.
(11) Remove nuts attaching booster to passenger
compartment side of dash panel.
(12) Slide booster forward and work it out of en-
gine compartment.
POWER BRAKE BOOSTER INSTALLATION
(1) Position booster on dash panel. Align booster
mounting studs with holes in panel and seat booster
(Fig. 9).
(2) In passenger compartment, install booster at-
taching nuts on mounting studs. Tighten attaching
nuts to 41 Nzm (30 ft. lbs.) torque.
(3) Install seal on master cylinder. Seal is slight
interference fit to help hold it in place.
Fig. 8 Pedal Travel Sensor Mounting
Fig. 9 Booster Attachment At Dash PanelÐYJ
Shown
JABS COMPONENT SERVICE 5 - 51

CAUTION: The pedal travel sensor and booster
must form a matched set. The cap on the sensor
plunger and the color dot on the booster shell are
color coded for identification, and to ensure they
are used as matched sets. Be sure the color on the
sensor cap and booster shell are the same before
installation. Refer to the Sensor Replacement infor-
mation before installing a new or original sensor.
(4) If new pedal travel sensor is being installed in
original booster, compare color dot on booster shell with
color of cap on sensor (Fig. 10). If both are same color,
proceed with installation. However, if colorsdo not
match, select correct color cap from kit supplied with
new sensor and install it on end of sensor plunger.
(5) Install O-ring on pedal travel sensor.
(6) Install sensor retaining ring on booster flange.
Be sure retaining ring is firmly seated.
(7) Insert sensor into booster. Be sure sensor is
fully seated and engaged in retaining ring.
(8) Connect booster push rod to brake pedal.
(9) Attach vacuum hose to booster check valve.
(10) Install master cylinder on booster. Tighten
cylinder attaching nuts to 25-30 Nzm (220-267 in.
lbs.) torque.
(11) Connect brakelines to master cylinder.
(12) Install combination valve bracket bolt if re-
moved.
(13) Connect reservoir hoses to HCU pipes.
(14) Connect sensor wires.
(15) Bleed brakes. Refer to procedure in this section.
(16) Install air cleaner and hoses.
ACCELERATION SENSOR REMOVAL
(1) On XJ models, tilt rear seat assembly forward
for access to sensor (Fig. 11).
(2) On YJ models, move driver seat forward or
rearward for access to sensor and mounting bracket
(Fig. 11).
(3) Disconnect sensor harness (Fig. 10).
(4) On XJ models, remove screws attaching sensor
to bracket. Then remove sensor.
(5) On YJ models, remove screws attaching sensor
bracket to floorpan. Then remove sensor from bracket.
ACCELERATION SENSOR INSTALLATION
(1) Note position of locating arrow on sensor. Sen-
sor must be positioned so arrow faces forward.
CAUTION: The sensor mercury switch will not func-
tion properly if the sensor is mispositioned. Verify
that the sensor locating arrow is pointing to the
front of the vehicle.
(2) Position sensor in mounting bracket (Fig. 10).
(3) Install and tighten sensor attaching screws to
2-4 Nzm (17-32 in. lbs.) torque.
(4) Connect harness to sensor. Be sure harness
connecter is firmly seated.
(5) Move seat back to normal position.
Fig. 10 Booster Push Rod And Pedal Travel Sensor
Fig. 11 Acceleration Sensor Mounting
5 - 52 ABS COMPONENT SERVICEJ

(5) Mark or tag HCU hydraulic lines for assembly
reference.
(6) Disconnect hydraulic lines at HCU.
(7) Move HCU harness and air cleaner hose pipe
aside for access to HCU bracket nuts.
(8) Remove single bolt and two nuts attaching
HCU to mounting bracket on inner fender panel
(Figs. 16 and 17).
(9) Remove HCU. Lift HCU up and off mounting
bracket studs. Then work HCU past brakelines and
master cylinder to remove it.
HCU INSTALLATIONÐXJ
(1) Connect master cylinder reservoir hoses to
HCU pipes.
(2) Position HCU assembly on mounting bracket
and install attaching nuts.(3) Connect hydraulic lines to HCU (Fig. 18). Line
fitting nuts and bosses on valve body ports are color
coded. Be sure lines are properly connected.
(4) Connect HCU harness wires to HCU.
(5) Check routing of HCU lines/hoses. Be sure
lines are not kinked and are clear of engine compo-
nents.
(6) Fill master cylinder reservoir with Mopar DOT
3 brake fluid or equivalent.
(7) Bleed brake system.
(8) Install air cleaner and hoses. Secure air cleaner
hose pipe to fender apron with clamp.
(9) Check brake pedal action. Bleed brakes again if
pedal is not firm (feels soft/spongy).
HCU REMOVALÐYJ
(1) Place shop towels or small container under
master cylinder reservoir hoses.
(2) Disconnect master cylinder reservoir hoses at
HCU.
(3) Disconnect all sensor and harness wires at
HCU.
(4) Disconnect brakelines at HCU (Fig. 19). Mark
or tag lines for installation reference.
(5) Remove bolt and nuts attaching HCU mount-
ing bracket to fender apron and remove HCU.
HCU INSTALLATIONÐYJ
(1) Position HCU on fender apron (Figs. 2 and 19)
and install attaching bolts/nuts.
(2) Connect brakelines to HCU.
(3) Connect harness and sensor wires to HCU.
(4) Connect master cylinder reservoir hoses to
HCU.
Fig. 16 HCU Mounting (Left Hand Drive XJ)
Fig. 17 HCU Mounting (Right Hand Drive XJ)
Fig. 18 HCU Hydraulic Line Connections
5 - 54 ABS COMPONENT SERVICEJ

(5) Fill and bleed brake system.
COMBINATION VALVE REPLACEMENTÐXJ
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 housing for access to valve,
if necessary.
(2) Remove bolt attached valve to master cylinder
(Fig. 20).
(3) Disconnect pedal travel sensor harness connec-
tor and move harness wires aside for working access
if necessary.
(4) Disconnect pressure differential switch wires at
valve.
(5) Disconnect hydraulic lines at valve and remove
valve from vehicle.
(6) Connect hydraulic lines to valve.
(7) Position valve bracket on master cylinder and
install bracket attaching bolt.(8) Reconnect pressure differential switch and
pedal travel sensor wires.
(9) Bleed brake system. Refer to procedure in this
section.
COMBINATION VALVE REPLACEMENTÐYJ
The combination valve mounting bracket is perma-
nently attached to the valve. The bracket and valve
are serviced as an assembly.
(1) Disconnect harness wires from combination
valve switch.
(2) Disconnect brakelines attached to combination
valve.
(3) Remove nuts attaching combination valve
bracket to master cylinder mounting studs (Fig. 19).
(4) Remove valve and bracket as assembly.
(5) Start all brakelines in combination valve by
hand. Tighten line fittings just enough to prevent
leaks.
(6) Position valve mounting bracket on studs.
(7) Install and tighten nuts that attach combina-
tion valve bracket to studs on power brake booster.
(8) Connect wires to combination valve switch.
(9) Fill and bleed brake system.
(10) Final-tighten brakeline fittings to 18-23 Nzm
(160-210 in. lbs.) torque after bleeding brakes.
Fig. 19 HCU Mounting (YJ)
Fig. 20 Combination Valve Mounting (XJ)
JABS COMPONENT SERVICE 5 - 55

(4) Using insulated pliers, hold the cable terminal
approximately 12 mm (1/2 in.) from the engine cylin-
der head or block while rotating the engine with the
starter motor. Observe the spark plug cable terminal
for an arc. If steady arcing occurs, it can be expected
that the ignition secondary system is operating cor-
rectly. If steady arcing occurs at the spark plug ca-
bles, but the engine will not start, connect the DRB
scan tool. Refer to the Powertrain Diagnostic Proce-
dures service manual for DRB operation.
FAILURE TO START TEST
To prevent unnecessary diagnostic time and wrong
test results, the previous Checking For Spark test
should be performed prior to this test.
WARNING: SET PARKING BRAKE OR BLOCK THE
DRIVE WHEELS BEFORE PROCEEDING WITH THIS
TEST.
(1) Unplug the ignition coil harness connector at
the coil (Fig. 14).
(2) Connect a set of small jumper wires (18 gauge
or smaller) between the ignition coil and coil electri-
cal connector (Fig. 15).
(3) Determine that sufficient battery voltage (12.4
volts) is present for the starting and ignition sys-
tems.
(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 shut down relay.
²If voltage is at 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 near battery voltage during
the entire 5 seconds, turn the key off. Remove the60-way connector (Fig. 16) 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 17.
Using the jumper,momentarilyground terminal-19
of the 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.
Fig. 14 Coil Harness ConnectorÐTypical
Fig. 15 Coil TerminalsÐTypical
Fig. 16 PCM 60-Way Connector
Fig. 17 Special Jumper Ground-to-Coil Negative
Terminal
JIGNITION SYSTEMS 8D - 13

INSTRUMENT PANEL AND GAUGES
GROUP INDEX
page page
INSTRUMENT PANEL AND GAUGESÐXJ..... 1INSTRUMENT PANEL AND GAUGESÐYJ.... 14
INSTRUMENT PANEL AND GAUGESÐXJE
CONTENTS
page page
INSTRUMENT CLUSTER DIAGNOSIS........ 3
INSTRUMENT CLUSTER GENERAL INFORMATION.. 1
INSTRUMENT CLUSTER SERVICE PROCEDURES... 5
SPECIFICATIONS....................... 13
INSTRUMENT CLUSTER GENERAL INFORMATION
INDEX
page page
4WD Indicator Lamp........................ 2
Anti-Lock Brake Indicator Lamp............... 2
Brake Indicator Lamp....................... 2
Coolant Temperature Gauge................. 1
Coolant Temperature Indicator Lamp........... 1
Fuel Gauge.............................. 2
Low Fuel Warning Lamp..................... 2Malfunction Indicator Lamp (Check Engine)...... 2
Oil Pressure Gauge....................... 1
Oil Pressure Indicator Lamp.................. 1
Speedometer/Odometer System.............. 2
Tachometer.............................. 2
Upshift Indicator Lamp...................... 2
Voltmeter............................... 1
With the ignition switch in the ON or START posi-
tion, voltage supplied to the instrument cluster is lim-
ited by fuse #17. The voltage is supplied to all the
gauges and indicator lamps through the instrument
cluster printed circuit.
With the ignition switch in the OFF position, volt-
age is not supplied to the instrument cluster and the
gauges do not indicate any vehicle condition.
VOLTMETER
The voltmeter measures battery or generator out-
put voltage, whichever is greater.
OIL PRESSURE GAUGE
The oil pressure gauge pointer position is controlled
by a magnetic field created by electrical current flow
through the coils within the gauge. A change in current
flow will change the magnetic field which changes the
pointer position. The oil pressure sender is a variable
resistor that changes electrical resistance with a change
in oil pressure (values shown in Specifications chart).
OIL PRESSURE INDICATOR LAMP
Voltage is supplied to one side of the indicator bulb
and the oil pressure switch is connected to the other
side. When oil pressure is too low the switch closes
providing a path to ground, and the indicator bulb
lights.
COOLANT TEMPERATURE GAUGE
The coolant temperature gauge pointer position is
controlled by a magnetic field created by electrical
current flow through the coils within the gauge. A
change in current flow will change the magnetic field
which changes the pointer position. The coolant tem-
perature sensor is a thermistor that changes electri-
cal resistance with a change in coolant temperature
(values shown in Specifications chart).
COOLANT TEMPERATURE INDICATOR LAMP
Voltage is supplied to one side of the indicator bulb
and the coolant temperature switch is connected to the
JINSTRUMENT PANEL AND GAUGES 8E - 1

other side. When coolant temperature is too high the
switch closes providing a path to ground, and the indi-
cator bulb lights.
TACHOMETER
The tachometer displays the engine speed (RPM).
With the engine running, the tachometer receives an
engine speed signal from the Powertrain Control
Module pin 43 (values shown in Specifications chart).
SPEEDOMETER/ODOMETER SYSTEM
The speedometer/odometer system consists of an elec-
tric speedometer and pushbutton reset odometer
mounted in the cluster. The system also includes the
wire harness from the cluster to the vehicle speed sen-
sor at the transmission, and the adapter and pinion in
the transmission. A signal is sent from a transmission
mounted vehicle speed sensor to the speedometer/odom-
eter circuitry through the wiring harness. Refer to
Group 21 - Transmission for selecting the proper pinion,
and selecting and indexing the proper adapter.
FUEL GAUGE
The fuel gauge pointer position is controlled by a
magnetic field created by electrical current flow through
the coils within the gauge. A change in current flow will
change the magnetic field which changes the pointer po-
sition. The fuel level sender is a variable resistor that
changes electrical resistance with a change of the level
of fuel in the tank (values shown in Specifications
chart).
LOW FUEL WARNING LAMP
The low fuel warning lamp will light when the fuel
level falls below approximately 4 gallons. A low fuel
warning module controls when the lamp will light.
When the module senses 66.5 ohms or less from the
fuel level sender for 10 continuous seconds, the lamp
will light. The lamp will remain on until the module
senses 63.5 ohms or more from the fuel level sender
for 20 continuous seconds.
UPSHIFT INDICATOR LAMP
Vehicles equipped with manual transmissions have an
optional upshift indicator lamp. The lamp is controlled
by the Powertrain Control Module. The lamp lights to
indicate when the driver should shift to the next high-
est gear for best fuel economy. The Powertrain Control
Module will turn the lamp off after 3 to 5 seconds if the
upshift is not performed. The lamp will remain off until
the vehicle stops accelerating and is brought back to the
range of lamp operation or shifted into another gear.
The indicator lamp is normally illuminated when
the ignition switch is turned ON and is turned off
when the engine is started. The lamp will be lighted
during engine operation according to engine speed
and load.
BRAKE INDICATOR LAMP
The brake indicator lamp warns the driver that the
parking brake is applied or that hydraulic pressure in
the split brake system is unequal.
Voltage is supplied through the brake indicator
bulb to 3 switches. A path to ground for the current
is available if:
²The brake warning switch is closed (with unequal
brake system hydraulic pressures), or
²
The ignition switch is in the START position (to test
the bulb), or
²The park brake switch is closed (with the parking
brake applied).
ANTI-LOCK BRAKE SYSTEM (ABS) INDICATOR
LAMP
The anti-lock brake system (ABS) lamp lights to in-
dicate a system self-check is in process at vehicle
start-up. If light remains on after start-up or comes
on and stays on while driving, it may indicate that
the ABS system has detected a malfunction or has
become inoperative.
4WD INDICATOR LAMP
COMMAND-TRAC 4WD
The PART TIME lamp lights when the vehicle is en-
gaged in four-wheel drive mode. Voltage is supplied to
one side of the indicator bulb. A switch in the transfer
case area is connected to the other side of the indicator
bulb. When the switch is closed, a path to ground is pro-
vided and the indicator bulb lights.
SELECT-TRAC 4WD
The four-wheel drive icon or FULL TIME lamp
lights when the vehicle is engaged in full time four-
wheel drive mode. The PART TIME lamp lights when
the vehicle is in part time four-wheel drive mode.
Voltage is supplied to one side of the indicators.
Switches in the transfer case area are connected to
the other side of the indicator bulbs. When a switch
is closed, a path to ground is provided and the indi-
cator bulb lights.
MALFUNCTION INDICATOR LAMP (CHECK ENGINE)
The Malfunction Indicator Lamp (Check Engine)
lights each time the ignition switch is turned ON and
stays on for 3 seconds as a bulb test.
If the PCM receives an incorrect signal or no signal
from certain sensors or emission related systems the
lamp is turned on (pin 32 of PCM). This is a warning
that the PCM has recorded a system or sensor mal-
function. In some cases when a diagnostic trouble
code is declared the PCM will go into a limp-in mode
in an attempt to keep the system operating. It sig-
nals an immediate need for service.
The lamp also can be used to display diagnostic
trouble codes (DTC). Cycle the ignition switch ON,
OFF, ON, OFF, ON within 5 seconds. This will allow
any trouble codes stored in the PCM memory to be
displayed in a series of flashes representing digits.
8E - 2 XJ INSTRUMENT PANEL AND GAUGESJ

INSTRUMENT CLUSTER DIAGNOSIS
INDEX
page page
4WD Indicator Inoperative................... 4
Anti-Lock Indicator......................... 4
Brake Indicator Inoperative.................. 4
Coolant Temperature Gauge Inoperative........ 3
Coolant Temperature Indicator Inoperative....... 3
Fuel Gauge Inoperative..................... 3
Gauges and Indicators Inoperative............ 3
Instrument Panel Lamps.................... 4
Low Fuel Warning Inoperative................ 4
Low Washer Indicator Inoperative............. 4Malfunction Indicator Lamp (Check Engine)...... 4
Oil Pressure Gauge Inoperative............... 3
Oil Pressure Indicator Inoperative............. 3
Radio/Clock Illumination.................... 4
Seat Belt Indicator........................ 4
Speedomete/Odometer Inoperative............. 3
Tachometer Inoperative..................... 3
Upshift Indicator Inoperative................. 4
Voltmeter Inoperative....................... 3
SPEEDOMETER/ODOMETER INOPERATIVE
(1) Check for continuity in the wire between the
vehicle speed sensor and cluster connector pin A5.
(2) With the ignition switch in the ON position,
check for battery voltage across pin A8 (B+) and pin
B2 (ground).
(3) Perform vehicle speed sensor test. Refer to the
appropriate vehicle Diagnostic Test Procedures man-
ual.
(4) If all the previous tests prove good, replace
speedometer/odometer.
GAUGES AND INDICATORS INOPERATIVE
(1) Remove and inspect fuse #17. Replace as re-
quired.
(2) Measure resistance at instrument cluster con-
nector terminal A3. Meter should read zero ohms. If
not, repair open to ground.
VOLTMETER INOPERATIVE
(1) Turn ignition switch to ON. Voltmeter should
read battery voltage. If not, go to step 2.
(2) Measure voltage at instrument cluster connec-
tor terminal A8. Meter should read battery voltage.
If OK, replace meter. If not, repair open to fuse #17.
OIL PRESSURE GAUGE INOPERATIVE
(1) Turn ignition switch to ON.
(2) Disconnect oil pressure sender connector (Fig.
1). Needle goes to H. If not, go to step 3.
(3) Touch oil pressure sender connector to ground.
Needle goes to L. If OK, replace sender. If not, repair
open to gauge (instrument cluster connector terminal
B7).
OIL PRESSURE INDICATOR INOPERATIVE
(1) Turn ignition switch to ON.
(2) Touch oil pressure switch connector to ground.
Lamp should light. If OK, replace switch. If bulb is
OK, repair open to instrument cluster connector ter-
minal B7.
COOLANT TEMPERATURE GAUGE INOPERATIVE
(1) Turn ignition switch to ON.
(2) Disconnect coolant temperature sender connec-
tor. Needle goes to C. If not, go to step 3.
(3) Touch coolant temperature sender connector to
ground. Needle goes to H. If OK, replace sender. If
not, repair open to gauge (instrument cluster connec-
tor terminal A1).
COOLANT TEMPERATURE INDICATOR
INOPERATIVE
(1) Turn ignition switch to ON.
(2) Touch coolant temperature indicator connector
to ground. Lamp should light. If OK, replace switch.
If bulb is OK, repair open to instrument cluster con-
nector terminal A1.
TACHOMETER INOPERATIVE
Tachometer input is from the Powertrain Control
Module pin 43. Use the DRB scan tool to test.
FUEL GAUGE INOPERATIVE
(1) Turn ignition switch to ON.
(2) Disconnect fuel gauge sender connector. Needle
should go to E.
Fig. 1 Oil Pressure Sending UnitÐ4.0L
JXJ INSTRUMENT PANEL AND GAUGES 8E - 3