ECU JEEP CHEROKEE 1995 Service Workshop Manual

ENGINE BLOCK HEATER
GENERAL INFORMATION
DESCRIPTION AND OPERATION
An optional engine block heater is available for all
models. The heater is equipped with a power cord.
The cord is attached to an engine compartment com-
ponent with tie-straps. The heater warms the engine
providing easier engine starting and faster warm-up
in low temperatures. The heater is mounted in a core
hole of the engine cylinder block (in place of a freeze
plug) with the heating element immersed in engine
coolant. Connect the power cord to a grounded 110-
120 volt AC electrical outlet with a grounded, three-
wire extension cord.
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
BLOCK HEATER SPECIFICATIONS
²2.5L 4-Cylinder Engine: 115 Volts 400 Watts
²4.0L 6-Cylinder Engine: 120 Volts 600 Watts
REMOVAL
Refer to correct illustration (Figures 11, 12 or 13)
when servicing block heater.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Drain coolant from radiator and engine cylinder
block.(2) Unplug power cord from block heater.
(3) Loosen screw in center of block heater (Figs. 11,
12 or 13).
(4) Remove block heater from cylinder block.
INSTALLATION
(1) Thoroughly clean the engine core hole and the
block heater seat.
(2) Insert block heater assembly into core hole
with element loop pointingUp.
(3) Seat block heater flush against block face.
Tighten mounting screw to 3.6 Nzm (32 in. lbs.)
torque.
(4) Fill cooling system with coolant. Pressurize sys-
tem and inspect for leaks.
(5) Plug power cord into block heater. Route cord
away from moving parts, linkages and exhaust sys-
tem components. Secure cord in place with tie-straps.
Fig. 13 Heater and CordÐYJ Models
Fig. 11 Heater and CordÐXJ with 2.5L 4-Cylinder
Engine
Fig. 12 Heater and CordÐXJ with 4.0L 6-Cylinder
Engine
7 - 44 ENGINE BLOCK HEATERJ

IGNITION-OFF DRAW
GENERAL INFORMATION
Ignition-Off Draw (IOD) refers to power being
drained from the battery with the ignition switch
turned OFF. A normal vehicle electrical system will
draw from 5 to 20 milliamps (0.005 - 0.020 amps).
This is with the ignition switch in the OFF position,
and all non-ignition controlled circuits in proper
working order. The 20 milliamps are needed to sup-
ply PCM memory, digital clock memory, and electron-
ically-tuned radio memory.
A vehicle that has not been operated for approxi-
mately 20 days, may discharge the battery to an in-
adequate level. When a vehicle will not be used for
20 days or more (stored), remove the IOD fuse in the
Power Distribution Center (PDC). This will reduce
battery discharging.
Excessive battery drain can be caused by:
²electrical items left on
²faulty or improperly adjusted switches
²internally shorted generator
²intermittent shorts in the wiring.
If the IOD is over 20 milliamps, the problem must
be found and corrected before replacing a battery. In
most cases, the battery can be charged and returned
to service.
DIAGNOSIS
Testing for high-amperage IOD must be per-
formed first to prevent damage to most milli-
amp meters.
(1) Verify that all electrical accessories are off.
Turn off all lamps, remove ignition key, and close all
doors. If the vehicle is equipped with illuminated en-
try or electronically-tuned radio, allow the systems to
automatically shut off (time out). This may take up
to 3 minutes.
(2) Determine that the underhood lamp is operat-
ing properly, then disconnect or remove bulb.
(3) Disconnect negative cable from battery.
(4) Connect a typical 12-volt test lamp (low-watt-
age bulb) between the negative cable clamp and the
battery negative terminal. Make sure that the doors
remain closed so that illuminated entry is not acti-
vated.The test lamp may light brightly for up to 3 min-
utes, or may not light at all, depending upon the ve-
hicle's electrical equipment. The term brightly, as
used throughout the following tests, implies the
brightness of the test lamp will be the same as if it
were connected across the battery.
The test lamp must be securely clamped to the neg-
ative cable clamp and battery negative terminal. If
the test lamp becomes disconnected during any part
of the IOD test, the electronic timer function will be
activated and all tests must be repeated.
(5) After 3 minutes the test lamp should turn off
or be dimly lit, depending upon the vehicle's electri-
cal equipment. If the test lamp remains brightly lit,
do not disconnect it. Remove each fuse or circuit
breaker (refer to Group 8W - Wiring Diagrams) until
test lamp is either off or dimly lit. This will isolate
each circuit and identify the source of the high-am-
perage draw.
If the test lamp is still brightly lit after disconnect-
ing each fuse and circuit breaker, disconnect the wir-
ing harness from the generator. If test lamp now
turns off or is dimly lit, see Charging System in this
group to diagnose faulty generator. Do not disconnect
the test lamp.
After high-amperage IOD has been corrected, low-
amperage IOD may be checked. It is now safe to in-
stall a milliamp meter to check for low- amperage
IOD.
(6) With test lamp still connected securely, clamp a
milliamp meter between battery negative terminal
and negative cable clamp.
Do not open any doors or turn on any electri-
cal accessories with the test lamp disconnected
or the milliamp meter may be damaged.
(7) Disconnect test lamp. Observe milliamp meter.
The current draw should not exceed 0.020 amp. If
draw exceeds 20 milliamps, isolate each circuit by re-
moving circuit breakers and fuses. The milliamp
meter reading will drop when the source of the draw
is disconnected. Repair this circuit as necessary,
whether a wiring short, incorrect switch adjustment
or a component failure is found.
8A - 10 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

CAUTION: On some models, two bolts are used to
secure the sensor to the transmission. These bolts
are specially machined to correctly space the unit
to the flywheel. Do not attempt to install any other
bolts.
(3) Connect the electrical connector to the sensor.
(4) Install clip on sensor wire harness.
(5) Install clip over fuel rail mounting stud. Install
clip mounting nut.
INSTALLATIONÐYJ MODELS WITH 4.0L
6-CYLINDER ENGINE AND AUTOMATIC
TRANSMISSION
(1) Install the sensor into the access hole on the
transmission.
(2) Install sensor mounting bolt (Fig. 6).
(3) Tighten sensor mounting bolt to 6-to-8 Nzm (50-
to-70 in. lbs.) torque.
(4) Connect the electrical connector to sensor.
(5) Install the clip to sensor wire harness.
(6) Install clip over fuel rail mounting stud. Install
clip mounting nut.
ENGINE COOLANT TEMPERATURE SENSOR
For an operational description, diagnosis and re-
moval/installation procedures, refer to Group 14,
Fuel System.
DISTRIBUTOR
GENERAL INFORMATION
All distributors contain an internal oil seal that
prevents oil from entering the distributor housing.
The seal is not serviceable.
Factory replacement distributors are equipped with
a plastic alignment pin already installed. The pin is
located in an access hole on the bottom of the distrib-
utor housing (Fig. 7). It is used to temporarily lock
the rotor to the cylinder number 1 position during in-
stallation. The pin must be removed after installing
the distributor.
The camshaft position sensor is located in the dis-
tributor on all engines (Fig. 8). For removal/installa-
tion procedures, refer to Camshaft Position Sensor.
Distributor removal is not necessary for sensor re-
moval.
Refer to figure 8 for an exploded view of the dis-
tributor.
A fork with a slot is supplied on the bottom of the
distributor housing where the housing base seats
against the engine block (Fig. 8). The centerline of
the slot aligns with the distributor holddown bolt
hole in the engine block. Because of the fork, the dis-
tributor cannot be rotated. Distributor rotation is not
necessary as all ignition timing requirements are
handled by the powertrain control module (PCM).The position of the distributor determines fuel syn-
chronization only. It does not determine ignition tim-
ing.
Do not attempt to modify this fork to attain
ignition timing.
Fig. 7 Plastic Alignment Pin
Fig. 8 DistributorÐ2.5L Or 4.0L EnginesÐTypical
JIGNITION SYSTEMS 8D - 19

motion. Never pull directly on the cable. Internal
damage to cable will result.
(2) Prior to removing the spark plug, spray com-
pressed air around the spark plug hole and the area
around the spark plug. This will help prevent foreign
material from entering the combustion chamber.
(3) Remove the spark plug using a quality socket
with a rubber or foam insert.
(4) Inspect the spark plug condition. Refer to
Spark Plugs in the Diagnostics/Service Procedures
section of this group.
PLUG CLEANING
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean-
ing, file the center electrode flat with a small point
file or jewelers file before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will re-
main on the spark plug insulator and will cause
plug misfire.
PLUG GAP ADJUSTMENT
Check the spark plug gap with a gap gauge tool. If
the gap is not correct, adjust it by bending the
ground electrode (Fig. 20).Never attempt to adjust
the gap by bending the center electrode.
SPARK PLUG GAP
²2.5L 4-Cylinder Engine Spark Plug Gap: .89 mm
(.035 in).
²4.0L 6-Cylinder Engine Spark Plug Gap: .89 mm
(.035 in).
PLUG INSTALLATION
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion. This may result
in a change in the spark plug gap, or a cracked por-
celain insulator.
When replacing the spark plug and ignition coil ca-
bles, route the cables correctly and secure them in
the appropriate retainers. Failure to route the cables
properly can cause the radio to reproduce ignition
noise. It could cause cross ignition of the spark plugs,
or short circuit the cables to ground.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten the spark plugs to 35-41 Nzm (26-30 ft.
lbs.) torque.
(3) Install spark plug cables over spark plugs.
SPARK PLUG SECONDARY CABLES
CAUTION: When disconnecting a high voltage cable
from a spark plug or from the distributor cap, twist
the rubber boot slightly (1/2 turn) to break it loose
(Fig. 19). Grasp the boot (not the cable) and pull it
off with a steady, even force.
Install cables into the proper engine cylinder firing
order (Figs. 21 or 22).
When replacing the spark plug and coil cables,
route the cables correctly and secure in the proper
retainers. Failure to route the cables properly can
cause the radio to reproduce ignition noise. It could
also cause cross ignition of the plugs, or short circuit
the cables to ground.
Fig. 19 Cable Removal
Fig. 20 Setting Spark Plug GapÐTypical
8D - 24 IGNITION SYSTEMSJ

nition switch. Install screws finger tight. Remove the
dimmer switch actuator rod securing-tape from steer-
ing column.
(8) Adjust dimmer switch as follows: Depress the
switch slightly and insert a 3/32-inch drill bit into
the adjustment hole (Fig. 11). This is done to prevent
horizontal switch movement.
(9) Move switch toward steering wheel to remove
any lash from switch actuator rod. Tighten dimmer
and ignition switch fasteners to 4 Nzm (35 in. lbs.)
torque.(10) Install the windshield wiper intermittent con-
trol module and its bracket (if equipped).
(11) Install the negative battery cable.
Test dimmer switch. Test ignition switch operation
in all switch positions. If equipped with a tilt steer-
ing column, test operation of dimmer switch and ig-
nition switch in all tilt positions.
Fig. 14 Detent PositionsÐNon-Tilt Steering Column
Fig. 15 Detent PositionsÐTilt Steering Column
JIGNITION SYSTEMS 8D - 31

(3) Reach under the instrument panel and depress
the switch shaft release/retainer button (Fig. 14).
Pull the switch control knob and shaft outward.
(4) Remove the headlamp switch retaining nut
from the front of the instrument panel (Fig. 15).(5) Disconnect the wire harness connector from the
switch.
(6) Remove the headlamp switch from the instru-
ment panel.
(7) Reverse removal procedures to install.
INSTRUMENT PANEL REMOVE/INSTALL
(1) Disconnect battery negative cable.
(2) Remove the following (Fig. 16):
²parking brake release handle
²lower heat/AC duct below steering column
²ash receiver
²lower instrument panel
²cluster bezel
²cluster assembly
²radio
²climate control panel
²instrument panel switches
²headlamp switch
²antenna connector
²blower motor resistors
²ground lead
²unplug glove box lamp
²defroster cowl outlet panel
Remove driver's side heat/AC outlet to gain
access to driver's side defroster cowl outlet
panel retaining clip to aid in removal (Fig. 17).
²instrument panel attaching bolts
²steering column attaching bolts
²instrument panel assembly.
The instrument panel wiring harness is at-
tached to the back of the instrument panel as-
sembly and must be installed correctly.
(3) To install instrument panel, position instru-
ment panel assembly on side mounting bolts (Fig.
18).
(4) Route wiring harnesses and secure instrument
panel assembly mounting points.
(5) Connect tube to lap cooler.
(6) Reverse removal procedures to complete instal-
lation.
Fig. 13 Printed Circuit And Cluster Connector
Fig. 14 Headlamp Switch Knob And Shaft Remove/
Install
Fig. 15 Headlamp Switch Remove/Install
8E - 20 INSTRUMENT PANEL AND GAUGESÐXJJ

(2) Carefully remove grille from speaker by placing
fingertips on outer circumference of grille and gently
prying straight down to disengage 4 mounting tabs.
(3) Drill out rivets securing speaker to sound bar.
(4) Lower speaker far enough to unplug wiring
from connector.
(5) Reverse removal procedures to install. Use new
rivets to secure speaker. Be certain that tabs on
speaker grille are inserted through slots in sound
bar.
SOUND BAR REMOVE/INSTALL - XJ
(1) Disconnect battery negative cable.
(2) Remove lens from cargo lamp housing.
(3) Remove screws securing left and right rear side
roof rail garnish moldings.
(4) Remove left and right rear side roof rail gar-
nish moldings.
(5) Remove 2 push-on retainers from pins inside
cargo lamp housing securing sound bar to rear roof
bow.
(6) Lower sound bar from roof area and remove
from vehicle.
(7) Reverse removal procedures to install. Use 2
new push-on retainers.
ANTENNA REMOVE/INSTALL - XJ
(1) Remove the fender inner splash panel mount-
ing nuts (Fig. 14) and move the panel aside to gain
access to the antenna base and cable.
The splash panel screws may be covered with
undercoating.
(2) Remove the antenna mast, nut and antenna
pad from the top of the fender (Fig. 15).
(3) Remove the passenger side kick panel.
(4) Disconnect the antenna lead (Fig. 16) by pull-
ing apart while twisting the metal connectors. DO
NOT PULL ON THE COAXIAL CABLE.
(5) Pull the rubber grommet out of the kick panel.(6) Remove the antenna assembly from inside the
wheel well.
(7) Reverse removal procedures to install.
(8) Verify antenna and radio operation.
Fig. 13 Trim Panel Remove - XJ
Fig. 14 Fender Inner Splash Panel Remove/Install -
XJ
Fig. 15 Nut and Antenna Pad Remove/Install - XJ
8F - 8 AUDIO SYSTEMSJ

(3) Remove screws holding speaker grille and
speaker to bar.
(4) Disconnect wires from speaker and remove
speaker.
(5) Reverse removal procedures to install.
SOUND BAR REMOVE/INSTALL - YJ
(1) Disconnect speaker harness connector located
on the passenger side at the sound bar (Fig. 19)
(2) Remove bolts attaching the sound bar side
flanges to the right and left side bars.
(3) Open zipper on sport bar cover.
(4) Remove bolts attaching the sound bar brackets
to the sport bar (located on the rear of the sport bar)
(Fig. 20). Slip brackets through the sport bar cover.
(5) Reverse removal procedures to install.
ANTENNA REMOVE/INSTALL - YJ
(1) Remove the radio. See Radio Remove/Install, in
this group for procedures.
(2) Remove three screws holding the antenna base
and pad to the body (Fig. 21).
(3) Pull the antenna and cable out of the vehicle.(4) To install the antenna, make sure the antenna
pad is placed over the cable and guide the cable un-
der the instrument panel.
(5) Secure the antenna base and pad with three
screws.
(6) Install the antenna lead into the radio and in-
stall the radio.
Fig. 19 Sound Bar Speaker Connector - YJ
Fig. 20 Sound Bar Attaching Bolt - YJ
Fig. 21 Antenna Remove/Install - YJ
8F - 10 AUDIO SYSTEMSJ

WARNING: THE USE OF VEHICLE SPEED CON-
TROL IS NOT RECOMMENDED WHEN DRIVING
CONDITIONS DO NOT PERMIT MAINTAINING ACONSTANT SPEED, SUCH AS IN HEAVY TRAFFIC
OR ON ROADS THAT ARE WINDING, ICY, SNOW
COVERED, OR SLIPPERY.
DIAGNOSIS
Before beginning diagnosis, perform a vehicle road
test to verify reports of speed control system mal-
function. The road test should include attention to
the speedometer. Speedometer operation should be
smooth and without flutter at all speeds.
Flutter in the speedometer indicates a problem
which might cause surging in the speed control sys-
tem. The cause of any speedometer problems should
be corrected before proceeding. Refer to Group 8E -
Instrument Panel and Gauges for speedometer diag-
nosis.
If a road test verifies a system problem and the
speedometer operates properly, check for:
(1) Loose or corroded electrical connections at the
servo. Corrosion should be removed from electricalterminals and a light coating of Mopar MultiPurpose
Grease, or equivalent, applied.
(2) Correct installation of the vacuum check valve
in the hose from servo to vacuum source. The word
VAC on the valve must point toward the vacuum
source.
(3) Loose or leaking vacuum hoses or connections.
(4) Secure attachment of both ends of the speed
control servo cable.
CAUTION: When test probing for voltage or conti-
nuity at electrical connectors, care must be taken
not to damage connector, terminals, or seals. If
these components are damaged, intermittent or
complete system failure may occur.
Fig. 1 Vehicle Speed Control System
8H - 2 VEHICLE SPEED CONTROL SYSTEMJ

SERVO CABLE REMOVE/INSTALL
(1) Remove air cleaner.
(2) Using finger pressure only, remove speed con-
trol cable connector at bellcrank by pushing connec-
tor off the bellcrank (Fig. 11). DO NOT try to pull
connector off perpendicular to the bellcrank.(3) Squeeze tabs on speed control cable and push
out of locking plate (Fig. 12). Unclip cable from cable
guide.
(4) Remove servo cable from servo as described in
Speed Control Servo Remove/Install.
(5) Reverse removal procedures to install.
VACUUM RESERVOIR REMOVE/INSTALL
(1) Remove vacuum hose connection at reservoir.
(2) Remove 2 screws securing reservoir from be-
neath front bumper.
(3) Remove reservoir.
(4) Reverse removal procedures to install. Tighten
mounting screws to 8.5 Nzm (75 in. lbs.).
Fig. 11 Servo Cable to Bellcrank Remove/Install
Fig. 12 Servo Cable to Locking Plate Remove/Install
8H - 10 VEHICLE SPEED CONTROL SYSTEMJ