ECO mode JEEP CHEROKEE 1994 Service Owner's Manual

voir. Fluid pressure is allowed to bleed off (decrease)
as needed to prevent wheel lock.
Once the period of high wheel slip has ended, the
ECU closes the outlet valve and begins a pressure in-
crease or hold cycle as needed.
Pressure Hold
Both solenoid valves are closed in the pressure hold
cycle (Fig. 12). Fluid apply pressure in the control
channel is maintained at a constant rate. The ECU
maintains the hold cycle until sensor inputs indicate
a pressure change is necessary.
Pressure Increase
The inlet valve is open and the outlet valve is
closed during the pressure increase cycle (Fig. 13).
The pressure increase cycle is used to counteract un-
equal wheel speeds. This cycle controls reapplication
of fluid apply pressure after a pressure decrease cy-
cle.
HCU PUMP AND PEDAL TRAVEL SENSOR
OPERATION
The HCU pump has two functions during antilock
braking. First, the pump supplies the extra volume
of fluid needed. And second, the pump maintains
brake pedal height. The fluid source for the pump is
the master cylinder reservoir. The reservoir and
HCU are interconnected by hoses.
The pump motor is activated by the ECU. How-
ever, the signal to run the pump actually comes from
the pedal travel sensor.
The pedal travel sensor is mounted in the forward
face of the brake booster (Fig. 14). The sensorplunger is actuated by movement of the booster dia-
phragm plate. The sensor has a total of seven pedal
positions, six of which are monitored. The six pedal
positions monitored range from full release to full ap-
ply. Each pedal position (toward full apply), gener-
ates an increasing degree of electrical resistance in
the sensor.
The ECU continuously monitors electrical resis-
tance at the pedal travel sensor. The ECU activates
the pump whenever sensor electrical resistance in-
creases during ABS mode braking.
Fig. 10 Three-Channel ABS Hydraulic Control Circuit
Fig. 11 Solenoid Valves In Pressure Decrease Cycle
5 - 44 ANTILOCK BRAKE SYSTEM OPERATIONJ

ABS COMPONENT SERVICE
INDEX
page page
Acceleration Sensor Installation.............. 52
Acceleration Sensor Removal............... 52
Combination Valve ReplacementÐXJ......... 55
Combination Valve ReplacementÐYJ......... 55
Component Serviceability................... 47
Correct Fluid Level....................... 48
ECU ReplacementÐXJ.................... 53
ECU ReplacementÐYJ.................... 53
Front Wheel Sensor Installation.............. 49
Front Wheel Sensor Removal............... 49
HCU InstallationÐXJ...................... 54
HCU InstallationÐYJ...................... 54HCU RemovalÐXJ....................... 53
HCU RemovalÐYJ....................... 54
Importance of Clean Brake Fluid............. 48
Master Cylinder Installation................. 50
Master Cylinder Removal.................. 50
Pedal Travel Sensor Service................ 51
Power Brake Booster Installation............. 51
Power Brake Booster Removal.............. 51
Rear Wheel Sensor Installation.............. 50
Rear Wheel Sensor Removal............... 49
Recommended Brake Fluid................. 48
Wheel Sensor Air Gap Adjustment........... 49
COMPONENT SERVICEABILITY
The ABS components are serviced as assemblies
(Figs. 1 and 2); they are not repairable. The follow-
ing ABS components can be replaced separately:
²center feed master cylinder
²master cylinder-to-booster seal
²power brake booster (includes matched pedal
travel sensor)
²booster check valve and grommet
²pedal travel sensor and select fit caps²combination valve
²HCU and pump motor assembly
²ECU
²acceleration sensor
²wheel sensors
²system wire harnesses
The axle shaft tone wheels are not serviceable. If a
tone wheel becomes damaged, it will be necessary to
replace the axle shaft, or disc brake rotor and hub
assembly on 2-wheel drive models.
Fig. 1 ABS Hydraulic Component Locations (XJ)
JABS COMPONENT SERVICE 5 - 47

PARKING BRAKES
INDEX
page page
General Service Information................ 56
Parking Brake Adjustment (XJ/YJ)............ 63
Parking Brake Cable Tensioner Replacement (XJ).61
Parking Brake Front Cable Replacement (YJ) . . . 62
Parking Brake Lever Installation
(XJ with Full Console)................... 60
Parking Brake Lever Installation
(XJ with Mini Console)................... 58
Parking Brake Lever Installation
(XJ Without Console).................... 60
Parking Brake Lever Removal
(XJ with Full Console).................... 59
Parking Brake Lever Removal
(XJ with Mini Console)................... 58
Parking Brake Lever Removal (XJ Without Console).60
Parking Brake Operation................... 56
Parking Brake Pedal Installation (YJ).......... 61
Parking Brake Pedal Removal (YJ)........... 61
Parking Brake Rear Cable Replacement (XJ) . . . 62
Parking Brake Rear Cable Replacement (YJ) . . . 63
GENERAL SERVICE INFORMATION
Parking brake adjustment is controlled by a
cable tensioner mechanism. The tensioner mech-
anism is used on 1991 through 1994 YJ models
and XJ models starting with 1992 models. The
cable tensioner, once adjusted at the factory,
will not need further adjustment under normal
circumstances. There are only two instances
when adjustment is required. The first is when a
new tensioner, or cables have been installed.
And the second, is when the tensioner and ca-
bles are disconnected for access to other brake
components.
PARKING BRAKE OPERATION
The rear brakes are utilized for the parking brake
function. They are actuated hydraulically during nor-
mal brake operation but are mechanically actuated
for parking brake operation.
Parking Brake Components
The rear brakeshoes are applied by a system of le-
vers and cables for parking brake operation. A foot
or hand operated lever in the passenger compartment
is the main application device. Actuating levers on
the secondary brakeshoes move the shoes directly
into contact with the drum braking surface. The ac-
tuating levers are interconnected by a system of ca-
bles and a tensioner mechanism. The tensioner
mechanism controls parking brake adjustment.
On XJ models, the cable tensioner is part of the le-
ver assembly. On YJ models, the tensioner and
equalizer are mounted in a bracket attached to the
underbody.
On YJ models, the parking brake front cable is at-
tached to the foot pedal at one end and the cable ten-
sioner at the other. The tensioner is connected to the
equalizer which is the connecting device for the rear
cables (Fig. 1).
On XJ models, the cable tensioner is connected di-rectly to the hand lever (a front cable is not used).
The tensioner rod is attached to the equalizer which
is the connecting point for the rear cables (Fig. 2).
The rear cables are connected to the actuating le-
ver on each secondary brakeshoe. The levers are at-
tached to the brakeshoes by a pin either pressed into,
or welded to the lever. A clip is used to secure the
pin in the brakeshoe. The pin allows each lever to
pivot independently of the brakeshoe.
Struts, installed between each brakeshoe, are used
to maintain shoe alignment and equal motion when
the parking brakes are applied. Each strut is
equipped with a combination tension and anti-rattle
spring.
Parking Brake Application
To apply the parking brakes, the foot pedal is
pressed downward, or the hand lever is pulled up-
ward, to an engaged position. This pulls the rear
brakeshoe actuating levers forward, by means of the
interconnected tensioner and cables.
As the actuating lever is pulled forward, the park-
ing brake strut (which is connected to both shoes),
exerts a linear force against the primary brakeshoe.
This action presses the primary shoe into contact
with the drum.
Once the primary shoe contacts the brake drum,
force exerted through the strut does not end. Instead,
further lever movement continues to exert force
against the strut; only this time, in a reverse direc-
tion. The strut force then causes the secondary shoe
to pivot into contact with the drum as well.
The brakeshoes will remain engaged with the
drum until the levers and cables are released. A gear
type ratcheting mechanism is used to hold the pedal
or lever in an applied position. Parking brake release
is accomplished by means of the release handle on
YJ models. Or by the hand lever release button on
XJ models.
5 - 56 PARKING BRAKESJ

CLUTCH
CONTENTS
page page
CLUTCH DIAGNOSIS..................... 3
CLUTCH SERVICE...................... 10GENERAL INFORMATION.................. 1
GENERAL INFORMATION
INDEX
page page
Clutch Component Lubrication................ 1
Clutch Components........................ 1Clutch Linkage Fluid....................... 1
Clutch Operation.......................... 2
CLUTCH COMPONENTS
MECHANICAL COMPONENTS
The clutch mechanism in XJ/YJ models with man-
ual transmission consists of a single, dry-type clutch
disc and a diaphragm style clutch cover. A hydraulic
linkage is used to operate the clutch disc and cover.
The transmission input shaft is supported in the
crankshaft by a bearing. A sleeve type release bear-
ing is used to engage and disengage the clutch cover
pressure plate.
The release bearing is operated by a release fork in
the clutch housing. The fork pivots on a ball stud
mounted inside the housing. The release fork is actu-
ated by a hydraulic slave cylinder mounted in the
housing. The slave cylinder is operated by a clutch
master cylinder mounted on the dash panel. The cyl-
inder push rod is connected to the clutch pedal.
The clutch disc has cushion springs in the disc hub.
The clutch disc facing is riveted to the hub. The fac-
ing is made from a non-asbestos material. The clutch
cover pressure plate is a diaphragm type with a one-
piece spring and multiple release fingers. The pres-
sure plate release fingers are preset during
manufacture and are not adjustable.
HYDRAULIC LINKAGE COMPONENTS
The hydraulic linkage consists of a clutch master
cylinder with integral reservoir, a clutch slave cylin-
der and an interconnecting fluid line.
The clutch master cylinder push rod is connected to
the clutch pedal. The slave cylinder push rod is con-
nected to the clutch release fork. The master cylinder
is mounted on the driver side of the dash panel ad-jacent to the brake master cylinder and booster as-
sembly. This positioning is similar for both left and
right hand drive models.
CLUTCH LINKAGE FLUID
The integral clutch master cylinder reservoir, slave
cylinder and fluid lines are prefilled with fluid prior
to assembly operations.
The hydraulic system should not require additional
fluid under normal circumstances. In fact,the reser-
voir fluid level will actually increase as normal
clutch wear occurs. For this reason, it is impor-
tant to avoid overfilling, or removing fluid from
the reservoir.
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 COMPONENT LUBRICATION
Proper clutch component lubrication is important
to satisfactory operation. Using the correct lubricant
and not overlubricating are equally important. Apply
recommended lubricant sparingly to avoid disc and
pressure plate contamination.
Clutch and transmission components requiring lu-
brication are:
²pilot bearing
²release lever pivot ball stud
²release lever contact surfaces
²release bearing bore
²clutch disc hub splines
²clutch pedal pivot shaft bore
²clutch pedal bushings
²input shaft splines
JCLUTCH 6 - 1

DIAGNOSIS
INDEX
page page
DRB Scan Tool........................... 5
On-Board Diagnostics (OBD)................. 4Preliminary Checks........................ 5
ON-BOARD DIAGNOSTICS (OBD)
FOR COOLING SYSTEM COMPONENTS
The powertrain control module (PCM) has been
programmed to monitor the certain following cooling
system components:
²If the engine has remained cool for too long a pe-
riod, such as with a stuck open thermostat, a Diag-
nostic Trouble Code (DTC) number 17 can be
observed at the Check Engine Lamp.
²If an open or shorted condition has developed in
the relay circuit controlling the electric radiator fan,
a Diagnostic Trouble Code (DTC) number 35 can be
observed at the Check Engine Lamp.
If the problem is sensed in a monitored circuit of-
ten enough to indicate an actual problem, a DTC is
stored. The DTC will be stored in the PCM memory
for eventual display to the service technician. If the
problem is repaired or ceases to exist, the PCM can-
cels the DTC after 51 engine starts.
Certain criteria must be met for a DTC to be en-
tered into PCM memory. The criteria may be a spe-
cific range of engine rpm, engine temperature and/or
input voltage to the PCM.
A DTC indicates that the PCM has recognized an
abnormal signal in a circuit or the system. A DTC
may indicate the result of a failure, but never iden-
tify the failed component directly.
It is possible that a DTC for a monitored circuit
may not be entered into memory even though a mal-
function has occurred. Refer to On-Board Diagnostics
(OBD) in Group 14, Fuel Systems for additional in-
formation.
ACCESSING DIAGNOSTIC TROUBLE CODES
A stored Diagnostic Trouble Code (DTC) can be dis-
played by cycling the ignition key On-Off-On-Off-On
within three seconds and observing the Malfunction
Indicator Lamp. This lamp was formerly referred to
as the Check Engine Lamp. The lamp is located on
the instrument panel.
They can also be displayed through the use of the
Diagnostic Readout Box (DRB) scan tool. The DRB
connects to the data link connector in the engine
compartment (Figs. 5 or 6). For operation of the
DRB, refer to the appropriate Powertrain Diagnostic
Procedures service manual.EXAMPLES:
²If the lamp flashes 1 time, pauses and flashes 7
more times, a flashing Diagnostic Trouble Code
(DTC) number 17 is indicated.
²If the lamp flashes 3 times, pauses and flashes 5
more times, a flashing Diagnostic Trouble Code
(DTC) number 35 is indicated.
After any stored DTC information has been ob-
served, the display will end with a flashing DTC
number 55. This will indicate the end of all stored
information.
Fig. 5 Data Link ConnectorÐYJ ModelsÐTypical
Fig. 6 Data Link ConnectorÐXJ ModelsÐTypical
7 - 4 COOLING SYSTEMJ

ERASING TROUBLE CODES
After the problem has been repaired, the DRB scan
tool must be used to erase a DTC. Refer to the ap-
propriate Powertrain Diagnostic Procedures service
manual for operation of the DRB scan tool.
DRB SCAN TOOL
For operation of the DRB scan tool, refer to the ap-
propriate Powertrain Diagnostic Procedures service
manual.
PRELIMINARY CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause.
1. PROLONGED IDLE, VERY HIGH AMBI-
ENT TEMPERATURE, SLIGHT TAIL WIND AT
IDLE, SLOW TRAFFIC, TRAFFIC JAMS, HIGH
SPEED, OR STEEP GRADES:
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.
²Increasing engine speed for more air flow is recom-
mended.2. TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
3. AIR CONDITIONING; ADD-ON OR AFTER
MARKET:
A maximum cooling package should have been or-
dered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer's specifications.
4. RECENT SERVICE OR ACCIDENT RE-
PAIR:
Determine if any recent service has been performed
on vehicle that may effect cooling system. This may
be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt(s)
²Brakes (possibly dragging)
²Changed parts (incorrect water pump rotating in
wrong direction)
²Reconditioned radiator or cooling system refilling
(possibly under-filled or air trapped in system).
If investigation reveals none of the above as a
cause for engine overheating complaint, refer to fol-
lowing Symptom and Action chart.
JCOOLING SYSTEM 7 - 5

CAUTION: Do not operate an engine without a ther-
mostat, except for servicing or testing.
ON-BOARD DIAGNOSTICS
XJ and YJ models are equipped with On-Board Di-
agnostics for certain cooling system components. Re-
fer to On-Board Diagnostics (OBD) in the Diagnosis
section of this group for additional information. If the
powertrain control module (PCM) detects low engine
coolant temperature, it will record a Diagnostic Trou-
ble Code (DTC) in the PCM memory. The DTC num-
ber for low coolant temperature is 17. Do not change
a thermostat for lack of heat as indicated by the in-
strument panel gauge or heater performance unless a
DTC number 17 is present. Refer to the Diagnosis
section of this group for other probable causes. For
other DTC numbers, refer to On-Board Diagnostics
in the General Diagnosis section of group 14, Fuel
Systems.
The DTC can also be accessed through the DRB
scan tool. Refer to the appropriate Powertrain Diag-
nostic Procedures manual for diagnostic information
and operation of the DRB scan tool.
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Drain the coolant from the radiator until the
level is below the thermostat housing.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUM-
BER 6094) (FIG. 14). SNAP-ON CLAMP TOOL (NUM-
BER HPC-20) MAY BE USED FOR LARGER
CLAMPS. ALWAYS WEAR SAFETY GLASSES
WHEN SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only an original equipment clamp
with matching number or letter.
(2) Remove radiator upper hose and heater hose at
thermostat housing.
(3) Disconnect wiring connector at engine coolant
temperature sensor.(4) Remove thermostat housing mounting bolts,
thermostat housing, gasket and thermostat (Fig. 15).
Discard old gasket.
(5) Clean the gasket mating surfaces.
INSTALLATION
(1) Install the replacement thermostat so that the
pellet, which is encircled by a coil spring, faces the
engine. All thermostats are marked on the outer
flange to indicate the proper installed position.
(a) Observe the recess groove in the engine cyl-
inder head (Fig. 16).
(b) Position thermostat in groove with arrow and
air bleed hole on outer flange pointing up.
(2) Install replacement gasket and thermostat
housing.
Fig. 14 Hose Clamp ToolÐTypical
Fig. 15 Thermostat Removal/Installation
7 - 14 COOLING SYSTEMJ

through the relay. When coolant temperature is be-
low 88ÉC (190ÉF), the PCM opens the ground path to
the relay. This will prevent the cooling fan from be-
ing energized.
Whenever the air conditioning is used, the PCM
engages the auxiliary cooling fan. It provides a
ground path to the cooling fan relay.
DIAGNOSIS
The powertrain control module (PCM) will enter a
diagnostic trouble code (DTC) number 35 in memory
if it detects a problem in the auxiliary cooling fan re-
lay or circuit. This will be read as a flashing signal
at the instrument panel mounted Malfunction Indica-
tor Lamp (formerly referred to as the Check Engine
Lamp). Refer to On-Board Diagnostics in Group 14,
Fuel Systems for information on accessing a DTC.
The DTC can also be accessed through the DRB
scan tool. Refer to the appropriate Powertrain Diag-
nostic Procedures manual for diagnostic information
and operation of the DRB scan tool.
REMOVAL
The auxiliary fan is attached to the radiator upper
crossmember behind the radiator.
(1) Remove the fan retaining bolts from radiator
upper crossmember (Fig. 41).
(2) Disconnect the electric fan connector.
(3) Lift fan straight up and out of vehicle.
INSTALLATION
(1) Align lower retaining tabs of fan shroud with
slots in bracket at bottom of radiator. Push fan down
into position.
(2) Tighten the mounting bolts to 4 Nzm (31 in.
lbs.) torque.
(3) Connect auxiliary cooling fan electrical connec-
tor.
TRANSMISSION OIL COOLERS
WATER-TO-OIL COOLER
All models equipped with an automatic transmis-
sion are equipped with a transmission oil cooler
mounted internally within the radiator tank. This in-
ternal cooler is supplied as standard equipment on
all models equipped with an automatic transmission.
Transmission oil is cooled when it passes through
this separate cooler. In case of a leak in the internal
radiator mounted transmission oil cooler, engine
coolant may become mixed with transmission fluid or
transmission fluid may enter engine cooling system.
Both cooling system and transmission should be
drained and inspected if the internal radiator
mounted transmission cooler is leaking.
Also refer to the section on Transmission Air-to-Oil
Coolers. This auxiliary air-to-oil cooler is an option
on most engine packages.
REPLACING WATER-TO-OIL COOLER IN
RADIATOR SIDE TANK
The internal transmission oil cooler located within
the radiator is not serviceable. If it requires service,
the radiator must be replaced.
Once the repaired or replacement radiator has been
installed, fill the cooling system and inspect for
leaks. Refer to the Refilling Cooling System and
Testing Cooling System For Leaks sections in this
group. If the transmission operates properly after re-
pairing the leak, drain the transmission and remove
the transmission oil pan. Inspect for sludge and/or
rust. Inspect for a dirty or plugged inlet filter. If
none of these conditions are found, the transmission
Fig. 40 PDCÐXJ Models
Fig. 41 Auxiliary FanÐRemove/Install
JCOOLING SYSTEM 7 - 29

and torque convertor may not require reconditioning.
Refer to Group 21 for automatic transmission servic-
ing.
AIR-TO-OIL COOLER
An auxiliary air-to-oil transmission oil cooler is
available with most engine packages.
On XJ and YJ models, the cooler is located in front
of the radiator or A/C condenser (if equipped) and be-
hind the grill (Figs. 42 or 43). It is mounted to the
front frame crossmember.The auxiliary oil coolers on all models operate in
conjunction with the internal radiator mounted main
oil cooler. The transmission oil is routed through the
main cooler first, then the auxiliary cooler, before re-
turning to the transmission.
REMOVAL/INSTALLATIONÐXJ MODELS
(1) Remove the grill. Refer to Group 23, Body.
(2) Place a drain pan below the transmission oil
cooler.
(3) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Fig. 42).
(4) Remove the two oil cooler mounting bolts (Fig.
42).
(5) Remove the oil cooler from vehicle.
(6) Reverse the preceding operation for installa-
tion. Tighten the two clamps 2 Nzm (15 in. lbs.)
torque.
REMOVAL/INSTALLATIONÐYJ MODELS
(1) Remove fan shroud and radiator. Refer to
Group 7, Cooling for procedures.
(2) Remove the air conditioning filter/drier mount-
ing bolts.
CAUTION: Before proceeding with the next step, be
sure to wear safety glasses. The A/C system is un-
der pressure even with the system off.
(3) Remove the A/C condenser mounting bolts (Fig.
44).
(4) Carefully tilt the A/C condenser rearward for
access to the auxiliary transmission oil cooler.
(5) Place a drain pan below the oil cooler.
(6) Remove the two hose clamps at oil cooler inlet
and outlet tubes (Fig. 43).
(7) Remove the two oil cooler mounting bolts (Fig.
43).
(8) Remove the oil cooler from vehicle.
(9) Reverse the preceding operation for installation.
Tighten the two clamps 2 Nzm (15 in. lbs.) torque.
Fig. 42 Auxiliary Air-To-Oil CoolerÐYJ Models
Fig. 43 Auxiliary Air-To-Oil CoolerÐXJ Models
Fig. 44 Condenser Mounting BoltsÐYJ Models
7 - 30 COOLING SYSTEMJ

IGNITION SYSTEMS
CONTENTS
page page
COMPONENT IDENTIFICATION/SYSTEM
OPERATION.......................... 1
COMPONENT REMOVAL/INSTALLATION..... 20DIAGNOSTICS/SERVICE PROCEDURES....... 8
IGNITION SWITCH...................... 30
SPECIFICATIONS....................... 33
COMPONENT IDENTIFICATION/SYSTEM OPERATION
INDEX
page page
Automatic Shut Down (ASD) Relay............ 1
Camshaft Position Sensor................... 1
Crankshaft Position Sensor.................. 2
Distributors.............................. 3
Engine Coolant Temperature Sensor........... 4
General Information........................ 1Ignition Coil.............................. 4
Intake Manifold Air Temperature Sensor........ 5
Manifold Absolute Pressure (MAP) Sensor...... 5
Powertrain Control Module (PCM)............. 6
Throttle Position Sensor.................... 6
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicle models by alphabetical designation
(XJ or YJ) or by the particular vehicle nameplate. A
chart showing a breakdown of alphabetical designa-
tions is included in the Introduction group at the be-
ginning of this manual.
This section of the group, Component Identifica-
tion/System Operation, will discuss ignition system
operation and will identify ignition system compo-
nents.
For diagnostic procedures and adjustments, refer to
the Diagnostics/Service Procedures section of this
group.
For removal and installation of ignition system
components, refer to the Component Removal/Instal-
lation section of this group.
For other useful information, refer to On-Board Di-
agnostics in the General Diagnosis sections of Group
14, Fuel System in this manual.
For operation of the DRB Scan Tool, refer to the
appropriate Powertrain Diagnostic Procedures ser-
vice manual.
An Ignition specifications section is included at the
end of this group. A general Maintenance Schedule
(mileage intervals) for ignition related items can be
found in Group 0, Lubrication and Maintenance. This
schedule can also be found in the Owners Manual.
IGNITION SYSTEMS
A multi-port, fuel injected engine is used on all
models. The ignition system is controlled by the Pow-
ertrain Control Module (PCM) on all engines. The
PCM was formerly referred to as the SBEC or engine
controller.
The ignition system consists of:
²Spark Plugs
²Ignition Coil
²Secondary Ignition Cables
²Ignition distributor (contains rotor and camshaft
position sensor)
²Powertrain Control Module (PCM)
²Crankshaft Position Sensor
AUTOMATIC SHUT DOWN (ASD) RELAY
The automatic shut down (ASD) relay is located in
the Power Distribution Center (PDC) near the bat-
tery (Fig. 1 or 2). As one of its functions, it will sup-
ply battery voltage to the ignition coil. The ground
circuit for the ASD relay is controlled by the Power-
train Control Module (PCM). The PCM regulates
ASD relay operation by switching the ground circuit
on-and-off.
CAMSHAFT POSITION SENSOR
The camshaft position sensor is located in the igni-
tion distributor (Figs. 3 or 4) on all engines.
The camshaft position sensor contains a hall effect
device called a sync signal generator to generate a
fuel sync signal. This sync signal generator detects a
JIGNITION SYSTEMS 8D - 1