bulb CHEVROLET DYNASTY 1993 Owner's Guide

CORNERING LAMP OR BULBÐAY/C-P-BODY
REMOVAL (FIG. 8)
(1) Raise vehicle.
(2) Remove bulb.
(3) To remove lamp assembly, remove the two re-
taining nuts.
INSTALLATION
Reverse the preceding operation.
TAIL, STOP, TURN SIGNAL, SIDE MARKER AND
BACK-UP LAMP OR BULBÐAY/C-P-BODY
REMOVAL (FIG. 9)
(1) Open the trunk lid and remove the tail panel
trim cover attaching screws and position the trim
cover away from the tail panel. (2) Disconnect rear end lamp wire connector and
push the harness grommet outward through the tail
panel. (3) Remove rear lamp assembly attaching screws
and separate the lamp assembly from the body. (4) Remove bulbs from lamp assembly.
INSTALLATION
Reverse the preceding operation.
LICENSE PLATE LAMP OR BULBÐAY/C-P-BODY
REMOVAL
(1) Remove the two screws retaining the lamp to
the bumper guard. (2) Remove the bulb from the socket assembly.
INSTALLATION
Reverse the preceding operation.
CENTER HIGH MOUNTED STOP LAMP BULB
(CHMSL)
REMOVAL AND INSTALLATION
(1) Open deck lid.
(2) From under the parcel shelf, rotate socket
counterclockwise, and pull the CHMSL socket and
bulb from the lamp. (3) Pull bulb from the socket.
INSTALLATION
Reverse the preceding operation.
CENTER HIGH MOUNTED STOP LAMP
REMOVAL (FIG. 10)
(1) Remove parcel shelf trim cover. Refer to Group
23, Body. (2) Remove two CHMSL attaching screws and sep-
arate the lamp from the parcel shelf.
INSTALLATION
Reverse the preceding operation.
Fig. 8 Cornering LampÐAY/C-P-Body
Fig. 9 Rear End LightingÐAY/C-P-Body
Fig. 10 Center High Mounted Stop LampÐTypical
8L - 24 LAMPS Ä

BULB APPLICATION TABLE
GENERAL INFORMATION
The following Bulb Application Table lists the
lamp title in bold print on the left side of the column.
The vehicle family and model codes are listed under
the lamp title. The trade number or part number is
listed on the right side of the column.
CAUTION: Do not use bulbs that have a higher can-
dle power than the bulb listed in the Bulb Applica-
tion Table. Damage to lamp can result. Do not touch halogen bulbs with fingers or other
possibly oily surfaces. Bulb life will be reduced .
EXTERIOR LAMPS
Back-up
AY/C-P ....................................................................921
AA/D-A, AC/C, AY/C-S .........................................922
AA/P-P-C, AJ/C, AP/D-P.....................................1156
AA/P-H, AC/D, AG/V, AY/C-P ...........................3157
Center High Mounted Stop
AA ...........................................................................921
AC, AG, AJ, AY, AP ............................................922
Cornering
AA, AY .................................................................3157
Fog
AA ......................................................................GE880
AP/D...................................................................GE893
AG, AP/P .................................................................H3
Front Side Marker
AA/P-H, AA/D, AC, AJ, AP, AY-S......................168
AA/P-PX, AA/C, AY-P ....................................194NA
Front Side Marker/Turn Sig.
AG....................................................................3157NA
Headlamp/Aero
AG, AJ-High Beam .............................................9005
AG, AJ-Low beam ...............................................9006
AA, AC/D, AP ......................................................9004
Headlamp/Sealed Low Beam
AC/C, AY ...........................................................H4703
Headlamp/Sealed High Beam
AC/C, AY ...........................................................H4701
License Plate
AA, AC/C, AG, AJ, AP, AY/C-S ..........................168
AC/D, AY/C-P.........................................................194
Park/Turn Signal
AC/C-D, AY/C-P, AY/C-S ..............................3157NA
AA/P-X-C, AC/C, AG, AY/C-P, AY/C-S ........194NA
AA/P-H-D ..............................................................3157
AJ, AP...................................................................2057
Rear Side Marker
AC/C, AG, AJ, AY/C-S-P ......................................168
AA/P-C-D, AC/D, AP, AY/CS (opt.) .....................916
Tail
AG ...........................................................................168
AJ, AY/C-P .............................................................916 Tail Reflector
AY ...........................................................................168
Tail/Stop/Turn Signal
AP ..........................................................................2057
AG, AC..................................................................3057
AA, AJ, AY ..........................................................3157
INTERIOR LAMPS
Some components have lamps that can only be ser-
viced by a Authorized Service Center (ASC) after the
component is removed from the vehicle. Contact local
dealer for location of nearest ASC. Chrysler vehicles
are equipped with a mechanical instrument cluster
(MIC) or an optional electronic instrument cluster
(EIC). If a bulb is unique to the MIC or EIC the ac-
ronym will follow the title.
INDICATOR LAMPS
Service procedures for the indicator lamps in the
instrument cluster are located in Group 8E, Instru-
ment Panel and Gauges. Air Bag (MIC)
AC, AY....................................................................103
AA, AG, AJ, AP ...............................................PC194
Antilock (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
Antilock (EIC)
AA, AY ..............................................................PC194
AJ ............................................................................103
Brake (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
Brake (EIC)
AA, AY ..............................................................PC194
AJ ............................................................................103
Check Engine (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
Check Engine (EIC)
AA, AY ..............................................................PC194
AJ ............................................................................103
Check Gauges
All .......................................................................PC194
Door Open
AA, AC, AY .............................................................74
AP ............................................................................161
AG, AJ ............................................................4437661
Fog Lamp (MIC)
AG ......................................................................PC194
High Beam (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
High Beam (EIC)
AA, AY ..............................................................PC194
Lamp Outage
8L - 38 LAMPS Ä

POWER MIRRORS
CONTENTS
page page
AUTOMATIC DAY/NIGHT INSIDE MIRROR .... 7
AUTOMATIC DAY/NIGHT INSIDE MIRROR WITH ULTRALIGHT HEADLAMP CONTROL ....... 7
GENERAL INFORMATION .................. 1
HEATED MIRROR ........................ 2
INSIDE MIRROR/READING LAMPS BULB/LENS REPLACEMENT ........................ 6
INSIDE MIRROR/READING LAMPS REPLACEMENT ........................ 6
MIRROR ASSEMBLY REPLACEMENTÐAA BODY.5
MIRROR ASSEMBLY REPLACEMENTÐ AC AND AY BODIES .................... 5
MIRROR ASSEMBLY REPLACEMENTÐAG BODY.5
MIRROR ASSEMBLY REPLACEMENTÐAJ BODY.5
MIRROR ASSEMBLY REPLACEMENTÐAP BODY.5
MIRROR MOTOR TEST PROCEDURE ........ 2
MIRROR SWITCH REPLACEMENTÐAA BODY . 3
MIRROR SWITCH REPLACEMENTÐAC AND AY BODIES .............................. 4
MIRROR SWITCH REPLACEMENTÐAG AND AJ BODIES .............................. 3
MIRROR SWITCH REPLACEMENTÐAP BODY . 4
MIRROR SWITCH TEST PROCEDURE ....... 2
TEST PROCEDURES ...................... 2
GENERAL INFORMATION
Electrically operated power mirrors are available
on all car lines. The mirrors are controlled by a sin-
gle switch assembly located either on the driver's
door trim panel or on the center console. There are three types of switches currently used,
each use s a L (left) R (right) for mirror selection (Fig.
1). Type I, which uses a rocker for mirror selection
and four buttons for mirror movement direction.
Type II, uses a toggle switch which is rotated clock-
wise for the Right mirror or counterclockwise for the
Left mirror selection, and moved UP, DOWN, LEFT,
or RIGHT for mirror movement direction. Type III, uses a paddle knob which is moved Left or Right for
mirror selection and four buttons for mirror move-
ment direction.
The motors which operate the mirrors are part of
the mirror assembly and cannot be replaced sepa-
rately. All vehicles are equipped with an Ignition-Off
Draw Connector which is used when the vehicles are
originally shipped from the factory. This connector,
which is located near the battery, helps to prevent
battery discharge during storage. For specific connec-
tor type and location, refer Group 8W, Wiring Dia-
grams.
Fig. 1 Power Mirror Switches
Ä POWER MIRRORS 8T - 1

(3) Disconnect mirror wiring connector near bot-
tom of door (Fig. 19). (4) Remove two mirror retaining nuts and screw
one, and pull mirror and harness from door. (5) For installation, reverse above procedure. Test
mirror for proper operation before installing door
trim panel.
INSIDE MIRROR/READING LAMPS REPLACEMENT
(1) Release locking tab on front side of mirror stay
by pushing down. While holding tab down, pull mir-
ror rearward to remove (Fig. 20). (2) Remove visor center attaching clips.
(3) Remove header end caps.
(4) Remove header trim.
(5) Disconnect wiring connector.
(6) For installation, reverse above procedure. En-
sure the mirror is fully locked into place.
INSIDE MIRROR/READING LAMPS BULB/LENS
REPLACEMENT
(1) Place a small thin blade tool in the notch at
the outside end of the lens housing and pry off the
lens housing. (2) Remove lamp socket from lens housing. Re-
move bulb from socket and replace if necessary. (3) Remove lens by applying pressure on locking
tabs to remove lens. (4) Replacing lens, set into place apply pressure
until it is locked into position. (5) For installation, reverse above procedure.
Fig. 16 Power Mirror AssemblyÐAJ Body
Fig. 17 Power Mirror WiringÐAP Body
Fig. 18 Power Mirror AssemblyÐAP Body
Fig. 19 Power Mirror AssemblyÐAC and AY Body
8T - 6 POWER MIRRORS Ä

FRAME AND BUMPERS
CONTENTS
page page
BUMPER AND FASCIA .................... 1 FRAME................................ 9
BUMPER AND FASCIA INDEX
page page
AA-Vehicle Front Bumper ................... 1
AA-Vehicle Rear Bumper ................... 5
AC-Vehicle Front Bumper ................... 2
AC-Vehicle Rear Bumper ................... 6
AG-Vehicle Front Bumper ................... 3
AG-Vehicle Rear Bumper ................... 7
AJ-Vehicle Front Bumper and Fascia .......... 4 AJ-Vehicle Rear Bumper
.................... 7
AP-Vehicle Front Bumper ................... 4
AP-Vehicle Rear Bumper ................... 7
AY-Vehicle Front Bumper ................... 5
AY-Vehicle Rear Bumper ................... 8
Safety Precautions and Warnings ............. 1
SAFETY PRECAUTIONS AND WARNINGS
WARNING: BUMPER ENERGY ABSORBER UNITS
CONTAIN PRESSURIZE GAS. DO NOT PUNCTURE
OR HEAT ABSORBER UNIT FOR ANY REASON.
PERSONAL INJURY CAN RESULT.
DO NOT VENTURE UNDER A HOISTED VEHICLE
THAT IS NOT SUPPORTED ON SAFETY STANDS.
PERSONAL INJURY CAN RESULT.
CAUTION: To avoid damaging a bright metal or
painted finish bumper or fascia, use a padded work
surface.
AA-VEHICLE FRONT BUMPER
REMOVAL (FIG. 1)
(1) Remove socket and bulb from park and turn
lamp. (2) Disconnect horn and fog lamp connectors (if
equipped). (3) Remove push-in fasteners holding sight shield
to vertical support in front of radiator. (4) Remove nuts holding fascia to fender, from be-
hind forward flange of fender. (5) Support front bumper assembly on suitable lift-
ing device and remove bolts holding bumper rein-
forcement to energy absorber units.
INSTALLATION
Reverse the preceding operation. Align bumper
height to approximately 3 mm (1/8 in.) gap to bottom
of head lamp assemblies and flush to front fenders
below the side marker lamps.
Fig. 1 Standard Front BumperÐAA-Vehicle
Ä FRAME AND BUMPERS 13 - 1

BUMPER AND WRAP-AROUND FASCIA REMOVAL (FIG. 2)
(1) Remove socket and bulb from park and turn
lamp. (2) Disconnect horn and fog lamp connectors (if
equipped). (3) Remove push-in plastic fasteners at forward
edge of front wheel opening. (4) Remove pal-nut fasteners from behind front
fenders rearward of the side marker lamp. (5) Remove push-in, fasteners holding sight shield
to vertical support in front of radiator. (6) Remove nuts holding fascia to fender, from be-
hind forward flange of fender. (7) Support front bumper on suitable lifting device
and remove bolts holding bumper reinforcement to
energy absorber units.
INSTALLATION
Reverse the preceding operation. Align bumper
height to approximately 3 mm (1/8 in.) gap to bottom
of head lamp assemblies and flush to front fenders
below the side marker lamps.
BUMPER OVERHAUL (FIG. 3)
(1) Position bumper assembly on a suitable padded
work surface to avoid damage to painted fascia. (2) Remove sight shield push-in, fasteners and sep-
arate shield from assembly. (3) Remove air dam screws and push-in fasteners
and lift dam out of retaining channels at ends of fas-
cia. Remove dam retaining channels and reinforce-
ments from fascia (if equipped). (4) Remove park and turn signal lamp assemblies,
see Group 8L, Lamps (5) Remove fog lamp bracket from bottom of
bumper reinforcement (if equipped). (6) Remove horns from back of bumper reinforce-
ment. (7) Remove lower air intake louver screws and
push-in fastener and separate louver from fascia. (8) Remove upper reinforcement to fascia attaching
bolts and separate reinforcement from fascia. (9) Straighten toy-tab fasteners holding horizontal
moulding to fascia and separate moulding from two
sided adhesive tape behind moulding. Remove moul-
ding from fascia.
BUMPER ASSEMBLY
Reverse the preceding operation.
AC-VEHICLE FRONT BUMPER
FRONT BUMPER AND STANDARD FASCIA REMOVALÐAC/D OR AC/C-H- BODY (FIG. 4)
(1) Remove nuts holding fascia to fender, from be-
hind forward flange of fender. (2) Support front bumper assembly on suitable lift-
ing device and remove bolts holding bumper rein-
forcement to energy absorber units. (3) Separate bumper from vehicle.
INSTALLATION
Reverse the preceding operation. Align bumper
height to fit flush to bottom of head lamp assemblies
and grille.
FRONT BUMPER OVERHAULÐAC\ OR AC/C-H- BODY (FIG. 4)
(1) Position bumper assembly on a suitable padded
work surface to avoid damage to painted fascia. (2) Remove push-in fasteners holding fascia to re-
inforcement. (3) Remove upper reinforcement to fascia attaching
bolts and separate reinforcement from fascia.
Fig. 2 Wrap-around Front BumperÐAA-Vehicle
Fig. 3 Front Bumper OverhaulÐAA-Vehicle
13 - 2 FRAME AND BUMPERS Ä

FRONT BUMPER REINFORCEMENT REMOVALÐAG-VEHICLE (FIG. 8)
(1) Remove bumper fascia as necessary to gain
clearance to remove bumper reinforcement. (2) Remove nuts holding bumper reinforcement to
energy absorber units. (3) Separate bumper reinforcement from vehicle.
carriage
INSTALLATION
Reverse the preceding operation
FRONT BUMPER ENERGY ABSORBERREMOVALÐAG-VEHICLE (FIG. 8)
(1) Remove front fascia and bumper reinforcement
as necessary to remove absorber unit. (2) Remove bolts holding energy absorber unit to
front closure panel. (3) Separate energy absorber from vehicle.
FRONT BUMPER ENERGY ABSORBERINSTALLATION
Reverse the preceding operation.
AJ-VEHICLE FRONT BUMPER AND FASCIA
REMOVAL (FIG. 9)
(1) Remove socket and bulb from park and turn
lamp. (2) Remove nuts holding fascia to fender, from be-
hind forward flange of fender. (3) Support front bumper assembly on suitable lift-
ing device and remove bolts holding bumper rein-
forcement to energy absorber units.
INSTALLATION
Reverse the preceding operation. Align bumper
height to approximately 5 mm (0.200 in.) gap to bot-
tom of grille and flush to front fenders on the sides.
AP-VEHICLE FRONT BUMPER
REMOVAL (FIG. 10)
(1) Raise vehicle and support on safety stands.
(2) Disconnect front park and turn signal lamp
wire connector. (3) Remove front side marker lamp socket from
lamp assembly and position socket out of the way. (4) Remove bolt holding front bumper fascia to
wheelhouse splash shield. (5) Remove nuts holding fascia to front fender.
(6) Support front bumper on lifting device.
(7) Remove bolts holding front bumper reinforce-
ment to energy absorber units. (8) Separate front bumper from vehicle.
INSTALLATION
Reverse the preceding operation.
Fig. 7 Headlamp Mounting PanelÐAG-Vehicle
Fig. 8 Front Bumper Reinforcement and Energy Absorber UnitÐ
Fig. 9 Front Bumper and FasciaÐAJ-Vehicle
13 - 4 FRAME AND BUMPERS Ä

The PCM removes the ground to the solenoid when
the engine reaches a specified temperature and the
time delay interval has occurred. When the solenoid is
de-energized, vacuum flows to the canister purge
valve. Vapors are purged from the canister and flow to
the throttle body. The purge solenoid is also energized during certain
idle conditions to update the fuel delivery calibration.
MALFUNCTION INDICATOR LAMP (CHECK
ENGINE)ÐPCM OUTPUT
The Malfunction Indicator lamp (instrument panel
Check Engine lamp) comes on each time the ignition
key is turned ON and stays on for 3 seconds as a bulb
test. The malfunction indicator lamp warns the opera-
tor that the PCM has entered a Limp-in mode. During
Limp-in-Mode, the PCM attempts to keep the system
operational. The malfunction indicator lamp signals
the need for immediate service. In limp-in mode, the
PCM compensates for the failure of certain components
that send incorrect signals. The PCM substitutes for
the incorrect signals with inputs from other sensors. Signals that can trigger the Malfunction Indi-
cator Lamp.
² Coolant Temperature Sensor
² Manifold Absolute Pressure Sensor
² Throttle Position Sensor
² Battery Voltage Input
² An Emissions Related System
² Charging system
The malfunction indicator lamp can also be used to
display diagnostic trouble codes. Cycle the ignition
switch on, off, on, off, on, within five seconds and any
diagnostic trouble codes stored in the PCM will be
displayed. Refer to the 2.2L/2.5L Single Point Fuel
InjectionÐOn-Board Diagnostics section in this group.
DATA LINK CONNECTORÐPCM OUTPUT
The data link connector provides the technician with
the means to connect the DRBII scan tool to diagnosis
the vehicle.
ELECTRIC ELECTRONIC GAS
RECIRCULATIONÐPCM OUTPUT
The electronic exhaust gas recirculation transducer
(EET) is a back pressure transducer/electric vacuum
solenoid assembly (Fig. 13). The EET assembly mounts
above the EGR valve (Fig. 14).
The solenoid turns the vacuum supply to the trans-
ducer on and off. The electric vacuum solenoid portion
of the EET energizes when the PCM provides a ground
path. When the solenoid energizes, vacuum is pre-
vented from flowing to the transducer. When the sole-
noid de-energizes, vacuum flows to the transducer. The
solenoid energizes during engine warm-up, closed
throttle (idle or cruise), wide open throttle, and rapid
acceleration/deceleration. If the solenoid wire con-
nector is disconnected, the EGR valve will oper-
ate at all times.
Fig. 12 EVAP Canister Purge Solenoid
Fig. 13 Electronic EGR Recirculation Transducer
Fig. 14 EGR Valve and Electric EGR Transducer
14 - 30 FUEL SYSTEMS Ä

SYSTEMS TEST
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE PERFORMING A TEST
WITH THE ENGINE OPERATING.
OBTAINING DIAGNOSTIC TROUBLE CODES
(1) Connect DRBII scan tool to the data link con-
nector located in the engine compartment near the
powertrain control module (PCM). (2) Start the engine if possible, cycle the transaxle
selector and the A/Cswitch if applicable. Shut off
the engine. (3) Turn the ignition switch on, access Read Fault
Screen. Record all the fault messages shown on the
DRBII scan tool. Observe the malfunction indicator
lamp (check engine lamp on the instrument panel).
The lamp should light for 3 seconds then go out (bulb
check).
STATE DISPLAY TEST MODE
The switch inputs used by the powertrain control
module (PCM) have only two recognized states,
HIGH and LOW. For this reason, the PCM cannot
recognize the difference between a selected switch po-
sition versus an open circuit, a short circuit, or a de-
fective switch. If the change is displayed, it can be
assumed that the entire switch circuit to the PCM is
functional. From the state display screen access ei-
ther State Display Inputs and Outputs or State Dis-
play Sensors.
STATE DISPLAY INPUTS AND OUTPUTS
Connect the DRBII scan tool to the vehicle and ac-
cess the State Display screen. Then access Inputs and
Outputs. The following is a list of the engine control
system functions accessible through the Inputs and
Outputs screen. Park/Neutral Switch (automatic transaxle only)
Speed Control Resume
Brake Switch
Speed Control On/Off
Speed Control Set
A/C Switch Sense
S/C (Speed Control) Vent Solenoid
S/C (Speed Control) Vacuum Solenoid
Torque Converter Clutch Solenoid (3 speed auto-
matic transaxle)
A/C Clutch Relay
EGR Solenoid
Auto Shutdown Relay
Radiator Fan Relay
Purge Solenoid
Malfunction Indicator (Check Engine) Lamp
STATE DISPLAY SENSORS
Connect the DRBII scan tool to the vehicle and ac-
cess the State Display screen. Then access Sensor
Display. The following is a list of the engine control
system functions accessible through the Sensor Dis-
play screen. Oxygen Sensor Signal
Coolant Temperature
Coolant Temp Sensor
Throttle Position
Minimum Throttle
Battery Voltage
MAP Sensor Reading
Idle Air Control Motor Position
Added Adaptive Fuel
Adaptive Fuel Factor
Barometric Pressure
Min Airflow Idl Spd
Engine Speed
Fault #1 Key-On Info
Module Spark Advance
Speed Control Target
Fault #2 Key-On Info
Fault #3 Key-On Info
Speed Control Status
Charging System Goal
Theft Alarm Status
Speed Control Switch Voltage
Map Sensor Voltage
Vehicle Speed
Oxygen Sensor State
MAP Gauge Reading
Throttle Opening (percentage)
Total Spark Advance
CIRCUIT ACTUATION TEST MODE
The circuit actuation test mode checks for proper
operation of output circuits or devices which the pow-
ertrain control module (PCM) cannot internally rec-
ognize. The PCM can attempt to activate these
outputs and allow an observer to verify proper oper-
ation. Most of the tests provide an audible or visual
indication of device operation (click of relay contacts,
spray fuel, etc.). With the exception of an intermit-
tent condition, if a device functions properly during
its test, it can be assumed that the device, its associ-
ated wiring, and its driver circuit are in working or-
der.
OBTAINING CIRCUIT ACTUATION TEST
Connect the DRBII scan tool to the vehicle and ac-
cess the Actuators screen. The following is a list of
the engine control system functions accessible
through Actuators screens. Stop All Tests
Ignition Coil #1
Fuel Injector #1
Idle Air Control Motor Open/Close
Ä FUEL SYSTEMS 14 - 45

ter mounting studs (Fig. 12). The top of the solenoid
has the word TOP on it. The solenoid will not oper-
ate unless it is installed correctly.
DATA LINK CONNECTORÐPCM OUTPUT
The data link connector provides the technician
with the means to connect the DRBII scan tool to di-
agnosis the vehicle.
FUEL INJECTORÐPCM OUTPUT
The Fuel Injectors are electric solenoids driven by
the PCM (Fig. 13). Based on sensor inputs, the PCM
determines when and how long the fuel injector
should operate. The amount of time an injector fires
is referred to as injector pulse width. The auto shut-
down (ASD) relay supplies battery voltage to the in-
jector. The PCM supplies the ground path. By
switching the ground path on and off, the PCM ad-
justs injector pulse width.
When the PCM supplies a ground path, a spring
loaded needle or armature lifts from its seat and fuel
flows through the injector orifice. Fuel is constantly supplied to the injector at regu-
lated 380 Kpa (55 psi). Unused fuel returns to the
fuel tank.
GENERATOR FIELDÐPCM OUTPUT
The PCM regulates the charging system voltage
within a range of 12.9 to 15.0 volts. Refer to Group
8A for charging system information.
IDLE AIR CONTROL MOTORÐPCM OUTPUT
The idle speed stepper motor is mounted on the
throttle body and is controlled by the PCM (Fig. 9).
The PCM adjusts engine idle speed through the idle
air control motor to compensate for engine load or
ambient conditions. The throttle body has an air bypass passage that
provides air for the engine at idle (the throttle blade is closed). The idle air control motor pintle protrudes
into the air bypass passage and regulates air flow
through it. The PCM adjusts engine idle speed by moving the
idle air control motor pintle in and out of the bypass
passage. The adjustments are based on inputs the
PCM receives from the throttle position sensor, speed
sensor (distributor pick-up coil), coolant temperature
sensor, and various switch operations (brake, park/
neutral, air conditioning). Deceleration die out is also
prevented by increasing airflow when the throttle is
closed quickly.
IGNITION COILÐPCM OUTPUT
The PCM provides a ground contact (circuit) for en-
ergizing the ignition coil. When the PCM breaks the
contact, the energy in the coil primary transfers to
the secondary causing the spark. The PCM will de-
energize the ASD relay if it does not receive an input
from the distributor pick-up. Refer to Auto Shutdown
(ASD) Relay/Fuel Pump RelayÐPCM Output in this
section for relay operation. The ignition coil is mounted on the hot box next to
the thermostat housing (Fig. 14).
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMPÐPCM OUTPUT
The malfunction indicator lamp (instrument panel
Check Engine lamp) comes on each time the ignition
key is turned ON and stays on for 3 seconds as a
bulb test. The malfunction indicator lamp warns the
operator that the PCM has entered a Limp-in mode.
During Limp-in-Mode, the PCM attempts to keep the
system operational. The malfunction indicator lamp
signals the need for immediate service. In limp-in
Fig. 13 Fuel Injector
Fig. 14 Ignition Coil
14 - 62 FUEL SYSTEMS Ä