1995 JEEP CHEROKEE turn signal

FRONT LIGHTING
INDEX
page page
Diagram Index............................ 3
Dimming Module........................... 1
Fog Lamps............................... 2
Headlamp Delay Module..................... 1Headlamp Relay........................... 1
Headlamps............................... 1
Parking Lamps............................ 2
HEADLAMPS
The headlamp switch has three positions: ON,
PARK (parking lamps) and OFF. Circuit A3 from fuse
12 in the PDC connects to the headlamp switch and
feeds circuit L7 through fuse 9 in the fuse block. Cir-
cuit L7 connects to the headlamp switch.
Circuit A3 also splices to feed circuit L11 through
fuse 10 in the fuse block. Circuit L11 connects to the
dimmer switch circuitry in the multi-function switch.
The headlamp switch has an internal circuit
breaker that connects circuit A3 to circuit F34. Cir-
cuit F34 connects to the headlamp relay.
HEADLAMP RELAY
When the headlamp switch is in the ON position it
connects circuit A3 from fuse 5 in the Power Distri-
bution Center (PDC) to circuit F34. Circuit A3 is
HOT at all times.
Circuit F34 supplies battery voltage to the coil and
contact sides of the headlamp relay. Circuit Z1 sup-
plies ground for the relay. When voltage is present on
circuit F34, the relay contacts close and connect cir-
cuit F39 to circuit F34.
Circuit F39 powers the headlamps through the
dimmer switch circuitry in the multi-function switch.
HEADLAMP SWITCH IN OFF OR PARKING
LAMP POSITION
Circuit L11 connects to the dimmer switch portion
of the multi-function switch. Circuit L11 supplies
power for the high beams on circuit L3 when the op-
erator flashes the headlamps with the turn signal
stalk of the multi-function switch.
HEADLAMP SWITCH IN ON POSITION
When the headlamp switch is in the ON position,
circuit A3 from fuse 12 in the Power Distribution
Center (PDC) connects to circuit F34. Circuit F34
connects to circuit F39 through the headlamp relay.
Circuit F39 feeds circuit L4 through the headlamp
dimmer switch circuitry in the multi-function switch.
Circuit L4 powers the low beam of the headlamps.
When the operator selects high beam operation
with the turn signal stalk of the multi-functionswitch, circuit L11 connects to the L3 circuit. Circuit
L3 powers high beam operation.
HEADLAMP GROUND
Circuit Z1 provides ground for both the right and
left headlamps. Circuit Z1 also supplies ground the
fog lamps, if equipped.
HELPFUL INFORMATION
²Check fuse 5 in the PDC.
²The headlamp switch has an internal circuit
breaker.
²Circuit L7 is double crimped at the headlamp
switch and branches to the chime module.
HEADLAMP DELAY MODULE
When the operator turns off the ignition switch and
the headlamp switch, the headlamp delay module
powers the headlamps for approximately 45 seconds.
When the ignition switch is in the RUN position,
circuit A21 powers circuit F87 through fuse 17 in the
fuse block. Circuit F87 supplies the IGNITION ON/
OFF signal to the headlamp delay module. Circuit Z1
provides ground for the module.
When the headlamp delay module activates, it con-
nects circuit X4 from fuse 5 in the fuse block to cir-
cuit F34. Circuit F34 connects to the circuit F39
through the headlamp relay. Circuit F39 powers the
headlamps through the headlamp dimmer switch cir-
cuit L4.
HELPFUL INFORMATION
Circuit A7 from fuse 3 in the PDC supplies voltage
to the fuse block bus bar that powers circuit X4
through the fuse in cavity 5.
DIMMING MODULE
Some vehicles are equipped with a dimming mod-
ule. The module is powered by the dimming relay.
In the RUN position, the ignition switch connects
circuit A1 from fuse 6 in the Power Distribution Cen-
ter (PDC) to circuit A38. Circuit A38 powers circuit
L170 through fuse 20 in the fuse block. Circuit L170
supplies power to the dimming relay.
When the headlamps are ON, circuit L90 from the
headlamp switch energizes the dimming relay. When
J8W-50 FRONT LIGHTINGÐXJ-RHD 8W - 50 - 1

DIAGRAM INDEX
Component Page
Chime/Buzzer Module......................8W-50-6
Dimming Module.........................8W-50-9
Dimming Relay..........................8W-50-8
Fog Lamp Relay........................8W-50-10
Fog Lamp Switch........................8W-50-10
Fuse 5 (Fuse Block).......................8W-50-7
Fuse 5 (PDC).........................8W-50-4, 8
Fuse 6 (PDC).........................8W-50-6, 8
Fuse 7 (PDC)..........................8W-50-10
Fuse 9 (Fuse Block).......................8W-50-4
Fuse 10 (Fuse Block)......................8W-50-7
Fuse 11 (Fuse Block)......................8W-50-8
Fuse 13 (PDC).........................8W-50-10
Fuse 20 (Fuse Block)......................8W-50-8
Fuse 26 (Fuse Block)......................8W-50-6
Headlamp Delay Module....................8W-50-7
Headlamp Dimmer Switch.................8W-50-4, 7
Headlamp Switch.....................8W-50-4, 7, 9
Headlamp Relay.........................8W-50-9
Ignition Switch........................8W-50-6, 8
Instrument Cluster........................8W-50-5
Left Fog Lamp.........................8W-50-10
Left Headlamp..........................8W-50-5
Left Marker Lamp........................8W-50-5
Left Tail, Stop and Turn Signal Lamp............8W-50-5
Overhead Console......................8W-50-4, 8
Right Fog Lamp........................8W-50-10
Right Headlamp.........................8W-50-5
Right Tail, Stop and Turn Signal Lamp...........8W-50-5
Telltale Connector (Instrument Cluster)...........8W-50-9
J8W-50 FRONT LIGHTINGÐXJ-RHD 8W - 50 - 3

REAR LIGHTING
TAIL LAMPS AND REAR LICENSE PLATE LAMPS
Circuit A3 from fuse 5 in the Power Distribution
Center (PDC) connects to a bus bar in the fuse block
which feeds circuit L7. Fuse 9 in the fuse block pro-
tects circuit L7.
The headlamp switch has three positions: ON,
PARK (parking lamps) and OFF, plus a dimmer
switch. When the headlamp switch is in the PARK or
ON position, the switch connects circuit L7 to circuit
L90. From the headlamp switch, circuit L90 branches
to power the front parking lamps and rear tail
lamps, side marker lamps, and rear license plate
lamps.
GROUND CIRCUIT
Circuit Z1 provides a ground for the parking lamps,
tail lamps, and rear license plate lamps.
HELPFUL INFORMATION
²Check fuse 5 in PDC.
²Check fuse 9 in the fuse block.
²When the headlamp switch is in the PARK or ON
position, circuit L7 also connects to circuit E2. Cir-
cuit E2 continues through fuse 25 in the fuse block.
Circuit E2 powers the illumination lamps.
STOP LAMPS AND CHMSL LAMPS
Circuit L9 from fuse 4 in the Power Distribution
Center (PDC) connects to the stop lamp switch.
When the operator depresses the brake pedal, the
stop lamp switch closes and connects circuit L9 to
circuit L50. Circuit L50 connects to the stop lamps
and center high mounted stop lamps (CHMSL). Cir-
cuit Z1 provides a ground for the stop lamps.
HELPFUL INFORMATION
²Check fuses 13 in the PDC.
²Check for continuity across the stop lamp switch
when it is closed.
BACK-UP LAMPS
In the START or RUN position, the ignition switch
connects circuit A1 from fuse 6 in the Power Distri-
bution Center (PDC) to circuit A21. Circuit A21 feeds
a bus bar in the PDC that powers circuit F12
through fuse 11.
Circuit F12 supplies power to the back-up lamp
switch. On automatic transmission equipped vehicles,
the back-up lamp switch is part of an assembly that
includes the PARK/NEUTRAL position switch. When
the operator puts the transmission in REVERSE, the
back-up lamp switch connects circuit F12 to circuit
L10. Circuit L10 feeds the back-up lamps. Circuit Z1
provides ground for the back-up lamps.
HELPFUL INFORMATION
²Check fuses 6 and 11 in the PDC.
²Check for continuity across the back-up lamp
switch when it is closed.
DIAGRAM INDEX
Component Page
Center High Mounted Stop Lamps (CHMSL).......8W-51-3
Fuse 4 (PDC)...........................8W-51-3
Fuse 5 (PDC)...........................8W-51-2
Fuse 6 (Fuse Block).......................8W-51-2
Fuse 6 (PDC)...........................8W-51-2
Fuse 9 (Fuse Block).......................8W-51-2
Headlamp Switch.........................8W-51-2
Ignition Switch..........................8W-51-2
Left Back-Up Lamp.......................8W-51-4
Left Side Marker Lamp.....................8W-51-4
Left Tail/Stop Lamp.......................8W-51-4
Left Turn Signal Lamp.....................8W-51-4
License Plate Lamp.......................8W-51-3
Park/Neutral Position Switch.................8W-51-2
Right Back-Up Lamp......................8W-51-5
Right Side Marker Lamp....................8W-51-5
Right Tail/Stop Lamp......................8W-51-4
Right Turn Signal Lamp....................8W-51-5
Stop Lamp Switch........................8W-51-3
J8W-51 REAR LIGHTINGÐXJ-RHD 8W - 51 - 1

TURN SIGNALS
TURN SIGNAL RELAY
In the RUN position, the ignition switch connects
circuit A1 from fuse 6 in the Power Distribution Cen-
ter (PDC) to circuit A21. Circuit A21 connects to the
turn signal relay.
Circuit L9 from fuse 4 in the PDC supplies battery
voltage to the relay. Circuit Z1 provides ground for
the relay.
Circuit L5 from the relay connects to the multi-
function switch to supply power to the turn signals.
The multi-function switch supplies voltage to the
turn signals and side marker lamps on circuits L60
and L61.
Circuit L12 from the relay connects to the multi-
function switch and the hazard flasher relay.
TURN SIGNALS
When the operator selects the right turn signal, the
multi-function switch connects power from circuit L5
to circuit L60. Circuit L60 feeds the right front and
right rear turn signal lamp. Circuit L60 also splices
to power the right turn signal indicator lamp on the
instrument cluster.
When the operator selects the right turn signal, the
multi-function switch connects power from circuit L5
to circuit L61. Circuit L61 feeds the left front and
left rear turn signal lamp. Circuit L61 also splices to
power the left turn signal indicator lamp on the in-
strument cluster.
Circuit Z1 provides ground for the turn signal
lamps.
HELPFUL INFORMATION
²The turn signal lamps are the same lamps used
for the hazard flasher.
²Check fuse 6 in the PDC.
HAZARD FLASHERS
When the operator selects the hazard flashers, the
multi-function switch connects circuit L12 from the
hazard flasher relay to circuits L60 and L61.
Circuit L60 feeds the right front and right rear
turn signal lamp. Circuit L60 also splices to power
the right turn signal indicator lamp on the instru-
ment cluster.
Circuit L61 feeds the left front and left rear turn
signal lamp. Circuit L61 also splices to power the left
turn signal indicator lamp on the instrument cluster.
Circuit Z1 provides ground for the hazard flasher
lamps.
HELPFUL INFORMATION
²The hazard flasher lamps are the same lamps
used for the turn signals.
DIAGRAM INDEX
Component Page
ABS Control Module......................8W-52-3
Flasher Relay...........................8W-52-2
Fuse 4 (PDC)...........................8W-52-2
Fuse 6 (PDC)...........................8W-52-2
Ignition Switch..........................8W-52-2
Instrument Cluster........................8W-52-2
Powertrain Control Module..................8W-52-3
Stop Lamp Switch........................8W-52-3
Transmission Control Module.................8W-52-3
Telltale Connector (Instrument Cluster)...........8W-52-4
Turn Signal Relay........................8W-52-4
Turn Signal Switch.......................8W-52-2
J8W-52 TURN SIGNALSÐXJ-RHD 8W - 52 - 1

TRAILER TOW
TRAILER TOW
The factory installed trailer tow system in this ve-
hicle uses three relays and a circuit breaker along
with the trailer tow wiring connector located below
the rear bumper.
Battery voltage for the trailer tow circuit breaker
and relays is supplied on circuit A11. This circuit is
HOT at all times and connects to the power accessory
tap in the fuse block. An in line 10 amp circuit pro-
tected breaker protects circuit A11 and the trailer
tow circuits. The trailer tow circuit breaker is located
in the left rear quarter panel.
STOP LAMP RELAY
Power for the coil side of the stop lamp relay is
supplied by circuit L50. This circuit connects to the
stop lamps. Ground for the coil side is supplied on
circuit Z1.
When the operator depresses the brake pedal, volt-
age flows through the coil of the relay to ground
causing the contacts in the relay to close connecting
circuits A11 and 95.
Circuit 95 connects to the left and right turn signal
relays. Voltage flows through the closed contacts in
the relays to the trailer tow connector.
RIGHT TURN RELAY
Power for the coil side of the right turn relay is
supplied by circuit L60. This circuit connects to the
right side turn signal lamps. Ground for the coil side
of the relay is supplied on circuit Z1.
When the operator turns the right turn signal ON,
power flows through the coil in the relay to ground
causing the contacts in the relay to switch from there
normally CLOSED position to connect circuits 94 and
L60.
Circuit 94 is the feed for the contact side of the re-
lay. Circuit L60 connects from the relay to the trailer
tow connector.
Circuit 94 is fed power through the normally
CLOSED side of the stop lamp relay and circuit A11.
The A11 circuit is HOT at all times and protected by
a 10 amp circuit breaker located in the left rear
quarter panel.
LEFT TURN RELAY
Power for the coil side of the left turn relay is sup-
plied by circuit L61. This circuit connects to the left
side turn signal lamps. Ground for the coil side of the
relay is supplied on circuit Z1.
When the operator turns the left turn signal ON,
power flows through the coil in the relay to ground
causing the contacts in the relay to switch from there
normally CLOSED position to connect circuits 94 and
L61.
Circuit 94 is the feed for the contact side of the re-
lay. Circuit L61 connects from the relay to the trailer
tow connector.
Circuit 94 is fed power through the normally
CLOSED side of the stop lamp relay and circuit A11.
The A11 circuit is HOT at all times and protected by
a 10 amp circuit breaker located in the right rear
quarter panel.
HELPFUL INFORMATION
²Check the In-Line circuit breaker
DIAGRAM INDEX
Component Page
Circuit Breaker (In-Line)....................8W-54-4
Electric Brake Provision....................8W-54-2
Fuse 1 (Fuse Block).......................8W-54-4
Fuse 3 (PDC)...........................8W-54-4
Left Turn Signal Relay.....................8W-54-3
Left Back-Up Lamp.......................8W-54-2
Left Side Marker Lamp.....................8W-54-2
Left Tail/Stop Lamp.......................8W-54-2
Left Turn Signal Lamp.....................8W-54-2
Right Turn Signal Relay....................8W-54-3
Stop Lamp Relay.........................8W-54-3
Trailer Tow Connector......................8W-54-2
J8W-54 TRAILER TOWÐXJ-RHD 8W - 54 - 1

MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT DESCRIPTION/SYSTEM
OPERATION
INDEX
page page
Air Cleaner.............................. 29
Air Conditioning (A/C) Clutch RelayÐPCM Output . 26
Air Conditioning (A/C) ControlsÐPCM Input...... 21
Auto Shutdown (ASD) RelayÐPCM Output...... 26
Automatic Shutdown (ASD) SenseÐPCM Input . . . 21
Battery VoltageÐPCM Input................. 21
Brake SwitchÐPCM Input................... 22
Camshaft Position SensorÐPCM Input......... 22
Crankshaft Position SensorÐPCM Input........ 22
Data Link ConnectorÐPCM Input............. 22
Data Link ConnectorÐPCM Output............ 27
EMR LampÐPCM Output................... 27
Engine Coolant Temperature SensorÐPCM Input . 23
Extended Idle SwitchÐPCM Input............. 23
Fuel InjectorsÐPCM Output................. 27
Fuel Pressure Regulator.................... 33
Fuel Pump RelayÐPCM Output.............. 27
Fuel Rail................................ 33
General Information....................... 19
Generator FieldÐPCM Output................ 27
Generator LampÐPCM Output............... 27
Idle Air Control (IAC) MotorÐPCM Output....... 27
Ignition Circuit SenseÐPCM Input............. 23
Ignition CoilÐPCM Output................... 28Intake Manifold Air Temperature SensorÐ
PCM Input............................. 22
Malfunction Indicator LampÐPCM Output....... 28
Manifold Absolute Pressure (MAP) SensorÐPCM
Input................................. 23
Open Loop/Closed Loop Modes of Operation..... 30
Oxygen (O2S) SensorÐPCM Input............ 24
Park/Neutral SwitchÐPCM Input.............. 24
Power Ground........................... 24
Power Steering Pressure SwitchÐPCM Input.... 24
Powertrain Control Module (PCM)............. 20
Radiator Fan RelayÐPCM Output............. 28
SCI ReceiveÐPCM Input................... 24
SCI TransmitÐPCM Output.................. 29
Sensor ReturnÐPCM Input.................. 25
Shift IndicatorÐPCM Output................. 29
Speed ControlÐPCM Input.................. 25
Speed ControlÐPCM Output................. 29
TachometerÐPCM Output................... 29
Throttle Body............................ 33
Throttle Position Sensor (TPS)ÐPCM Input...... 25
Torque Converter Clutch RelayÐPCM Output.... 29
Vehicle Speed SensorÐPCM Input............ 25
GENERAL INFORMATION
All 2.5L 4-cylinder and 4.0L 6-cylinder engines are
equipped with sequential Multi-Port Fuel Injection
(MFI). The MFI system provides precise air/fuel ra-
tios for all driving conditions.
The Powertrain Control Module (PCM) operates
the fuel system. The PCM was formerly referred to
as the SBEC or engine controller. The PCM is a pre-
programmed, dual microprocessor digital computer. It
regulates ignition timing, air-fuel ratio, emission con-
trol devices, charging system, speed control, air con-
ditioning compressor clutch engagement and idle
speed. The PCM can adapt its programming to meet
changing operating conditions.
Powertrain Control Module (PCM) Inputsrep-
resent the instantaneous engine operating conditions.
Air-fuel mixture and ignition timing calibrations for
various driving and atmospheric conditions are pre-
programmed into the PCM. The PCM monitors and
analyzes various inputs. It then computes engine fuel
and ignition timing requirements based on these in-
puts. Fuel delivery control and ignition timing will
then be adjusted accordingly.
Other inputs to the PCM are provided by the brake
light switch, air conditioning select switch and the
speed control switches. All inputs to the PCM are
converted into signals.
Electrically operated fuel injectors spray fuel inprecise metered amounts into the intake port directly
above the intake valve. The injectors are fired in a
specific sequence by the PCM. The PCM maintains
an air/fuel ratio of 14.7 to 1 by constantly adjusting
injector pulse width. Injector pulse width is the
length of time that the injector opens and sprays fuel
into the chamber. The PCM adjusts injector pulse
width by opening and closing the ground path to the
injector.
Manifold absolute pressure (air density) and engine
rpm (speed) are the primary inputs that determine
fuel injector pulse width. The PCM also monitors
other inputs when adjusting air-fuel ratio.
Inputs That Effect Fuel Injector Pulse Width:
²Exhaust gas oxygen content
²Engine coolant temperature
²Manifold absolute pressure (MAP)
²Engine speed
²Throttle position
²Battery voltage
²Air conditioning selection
²Transmission gear selection (automatic transmis-
sions only)
²Speed control
The powertrain control module (PCM) adjusts igni-
tion timing by controlling ignition coil operation. The
ignition coil receives battery voltage when the igni-
tion key is in the run or starter position. The PCM
JFUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATION 14 - 19

provides a ground for the ignition coil. The coil dis-
charges when the PCM supplies a ground. By switch-
ing the ground path on and off, the PCM regulates
ignition timing.
The sensors and switches that provide inputs to
the powertrain control module (PCM) comprise the
Engine Control System. It is also comprised of the
PCM Outputs (engine control devices that the are op-
erated by the PCM).
SYSTEM DIAGNOSIS
The powertrain control module (PCM) tests many
of its own input and output circuits. If a Diagnostic
Trouble Code (DTC) is found in a major system, this
information is stored in the PCM memory. Refer to
On-Board Diagnostics in the MFI SystemÐGeneral
Diagnosis section of this group for DTC information.
POWERTRAIN CONTROL MODULE (PCM)
The PCM operates the fuel system. The PCM was
formerly referred to as the SBEC or engine control-
ler. The PCM is a pre-programmed, dual microproces-
sor digital computer. It regulates ignition timing, air-
fuel ratio, emission control devices, charging system,
speed control, air conditioning compressor clutch en-
gagement and idle speed. The PCM can adapt its
programming to meet changing operating conditions.
On XJ models, the PCM is located in the engine
compartment next to the air cleaner (Fig. 1). On YJ
models, the PCM is located in the engine compart-
ment behind the windshield washer fluid reservoir
(Fig. 2).
The PCM receives input signals from various
switches and sensors. Based on these inputs, the
PCM regulates various engine and vehicle operations
through different system components. These compo-
nents are referred to as PCM Outputs. The sensors
and switches that provide inputs to the PCM are con-
sidered PCM Inputs.The PCM adjusts ignition timing based upon in-
puts it receives from sensors that react to: engine
rpm, manifold absolute pressure, coolant tempera-
ture, throttle position, transmission gear selection
(automatic transmission), vehicle speed and the
brake switch.
The PCM adjusts idle speed based on inputs it re-
ceives from sensors that react to: throttle position,
vehicle speed, transmission gear selection, coolant
temperature and from inputs it receives from the air
conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts
ignition coil dwell. The PCM also adjusts the gener-
ator charge rate through control of the generator
field and provides speed control operation.
Powertrain Control Module (PCM) Inputs:
²Generator output
²A/C request (if equipped with factory A/C)
²A/C select (if equipped with factory A/C)
²Auto shutdown (ASD) sense
²Intake manifold air temperature sensor
²Battery voltage
²Brake switch
²Engine coolant temperature sensor
²Crankshaft position sensor
²Ignition circuit sense (ignition switch in run posi-
tion)
²Manifold absolute pressure sensor
²Overdrive/override switch
²Oxygen sensor
²Park/neutral switch (auto. trans. only)
²SCI receive (DRB scan tool connection)
²Speed control resume switch
²Speed control set switch
²Speed control on/off switch
²Camshaft position sensor signal
²Throttle position sensor
²Vehicle speed sensor
²Sensor return
²Power ground
Fig. 1 PCM LocationÐXJ Models
Fig. 2 PCM LocationÐYJ Models
14 - 20 FUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATIONJ

SPEED CONTROLÐPCM INPUT
The speed control system provides three separate
inputs to the powertrain control module (PCM); On/
Off, Set and Resume. The On/Off input informs the
PCM that the speed control system has been acti-
vated. The Set input informs the PCM that a fixed
vehicle speed has been selected. The Resume input
indicates to the PCM that the previous fixed speed is
requested.
The speed control operating range is from 50 km/h
to 142 km/h (35 to 85 mph). Inputs that effect speed
control operation are:
²Brake switch position
²Park/neutral switch
²Vehicle speed sensor
²Throttle position sensor
Refer to Group 8H for further speed control infor-
mation.
SENSOR RETURNÐPCM INPUT
Sensor Return provides a low noise ground refer-
ence for all system sensors.
THROTTLE POSITION SENSOR (TPS)ÐPCM INPUT
The throttle position sensor (TPS) is mounted on
the throttle body (Figs. 14 or 15). The TPS is a vari-
able resistor that provides the powertrain control
module (PCM) with an input signal (voltage) that
represents throttle blade position. The sensor is con-
nected to the throttle blade shaft. As the position of
the throttle blade changes, the resistance of the TPS
changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from 1 volt
at minimum throttle opening (idle), to 4 volts at wide
open throttle. Along with inputs from other sensors,the PCM uses the TPS input to determine current
engine operating conditions. In response to engine
operating conditions, the PCM will adjust fuel injec-
tor pulse width and ignition timing.
VEHICLE SPEED SENSORÐPCM INPUT
The vehicle speed sensor (Fig. 16) is located in the
extension housing of the transmission (2 wheel drive)
or on the transfer case extension housing (4 wheel
drive). The sensor input is used by the powertrain
control module (PCM) to determine vehicle speed and
distance traveled.
The speed sensor generates 8 pulses per sensor
revolution. These signals, in conjunction with a
closed throttle signal from the throttle position sen-
sor, indicate a closed throttle deceleration to the
PCM. When the vehicle is stopped at idle, a closed
throttle signal is received by the PCM (but a speed
sensor signal is not received).
Under deceleration conditions, the PCM adjusts the
idle air control (IAC) motor to maintain a desired
MAP value. Under idle conditions, the PCM adjusts
the IAC motor to maintain a desired engine speed.
Fig. 13 Power Steering Pump Pressure SwitchÐXJ
Models
Fig. 14 Throttle Position SensorÐ2.5L Engine
Fig. 15 Throttle Position SensorÐ4.0L Engine
JFUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATION 14 - 25