ignition CHEVROLET DYNASTY 1993 Service Manual

CONDITION: MOTOR WILL STOP WHEREVER IT IS, WHEN COLUMN SWITCH IS PUT IN OFFPOSITION. THE WIPERS DO NOT CONTINUERUNNING TO PARK POSITION
PROCEDURE
(1) Remove motor wiring connector and clean ter-
minals. Reconnect connector and test motor.If prob-
lem persists, proceed to Step 2. (2) Set wiper switch to OFF position. Disconnect
motor wiring connector. Connect a voltmeter or test
lamp to the motor ground strap. Connect the other
lead to terminal 2 of wiring connector. (a) If voltage is not present, check for an open
circuit in the wiring harness or wiper control
switch. (b) If voltage is present, proceed to step 3.
(3) Connect an ohmmeter or continuity tester be-
tween terminals 3 and 1 (Fig. 14). (a) If there is continuity between these termi-
nals, the problem is a defective motor. (b) If there is no continuity, the problem is an
open circuit in the wiper control switch or wiring
harness.
REAR WIPER MOTORÐAG BODY TEST
The following test is used in order to locate and
then repair liftgate wiper motor defects. Refer to
Group 8W, Wiring Diagrams for liftgate wiper motor
wiring schematic. (1) Remove lower cover on liftgate (Fig. 15).
(2) Disconnect feed connector from wiper motor.
(3) With ignition switch in ON position, check for
battery voltage at blue wire. (4) With ignition switch in ON position and wiper
switch ON, check for battery voltage at blue and
brown wire. If battery voltage is not present in steps
3 and 4, check fuse, liftgate wiper switch and wiring. (5) With ignition switch in ON position, and wiper
switch in OFF position, check for battery voltage be-
tween blue and brown wires. If battery voltage is not
present, check ground wire to liftgate switch. (6) If battery voltage is present in steps 3 and 4,
replace motor.
FRONT WIPER MOTOR ASSEMBLYÐAG and AJ
BODIES
REMOVAL
(1) Park system.
(2) Open the hood assembly.
(3) Remove wiper arms and blades, disconnect
hoses from tee connector (Fig. 16).
Fig. 13 One Jumper Wire Between Terminal 1 and 3. One Jumper Wire Between Terminal 2 and Battery positive
Fig. 14 Ohmmeter Between Terminals 3 and 1
Fig. 15 Liftgate Lower Cover
8K - 6 WINDSHIELD WIPER AND WASHER SYSTEMS Ä

CONDITION: WIPERS START TO WIPE, BUT STOP BEFORE ONE COMPLETE CYCLE ANDDO NOT RETURN TO PARK POSITION
PROCEDURE
(1) Verify that motor will park when the column
switch is put in the OFF position. (2) Set wiper control switch to maximum DELAY
and allow motor to run until it stops during the wipe
cycle. When motor stops, disconnect 25-way blue con-
nector from the body controller. (3) Connect positive lead of voltmeter to pin 20 of
blue connector and negative lead to the metal case of
the body controller. (a) If voltmeter reads 0, check wiring for an open
circuit. (b) If voltmeter reads 10 to 15 volts, proceed to
step 4.
(4) Using an ohmmeter or continuity tester; (a) Check for continuity between pins 20 and 24
of blue connector of the body controller. (b) Reverse ohmmeter leads on pins 20 and 24,
again checking for continuity. (c) If continuity between pins 20 and 24 is not
observed in both steps a and b, replace the body
controller.
CONDITION: EXCESSIVE DELAY OF MORE THAN 30 SECONDS OR INADEQUATEVARIATION IN DELAY
PROCEDURE
(1) Variations in delay should be as follows: (a) Minimum delay control to extreme counter-
clockwise position before first detent of 1/2 to 2 sec-
onds. (b) Maximum delay control to extreme clockwise
position before OFF detent of 15 to 25 seconds.
(2) If there is excessive delay or no variations in
delay, remove the wiper motor wiring harness while
the motor is parked in the OFF position. (3) Remove 25-way blue connector from the body
controller. (4) Set wiper control switch to maximum DELAY
position. (5) With ignition switch in ON position, measure
voltage between pin 9 of black connector and a good
ground. (a) If voltmeter reads 0, proceed to step 6.
(b) If voltmeter reads 10 to 15 volts, proceed to
step 7.
(6) Set wiper control switch to minimum DELAY
position and measure voltage between pin 9 of blue
connector and a good ground. If voltmeter reads 0,
check for an open circuit in the intermittent wipe
wiring harness. (7) Remove wiper motor circuit fuse. (8) Using an ohmmeter, measure the resistance be-
tween pins 9 and 22 of the body controller 25-way
black connector. Set the wiper control switch first to
minimum DELAY and then maximum DELAY. (a) If resistance reading at minimum DELAY
setting is between 0 and 15 ohms, and at maxi-
mum DELAY setting the resistance is between
240,000 and 400,000 ohms, replace the body con-
troller. (b) If the resistance values above are not ob-
tained, replace the wiper control switch.
CONDITION: WIPERS DO NOT RUN CONTINUALLY WHEN WASH CONTROL ISOPERATED DURING DELAY MODE
PROCEDURE
(1) Disconnect 25-way blue connector from the
body controller (2) Using a voltmeter, connect the positive lead to
pin 10 of the (Black) connector. Connect negative
lead to the body computer metal case. (3) Set wiper control switch to DELAY position.
(4) Depress wash switch.
(5) If voltage reads 0, check switch relay and wir-
ing. (6) If voltage is between 10 and 15 volts, the prob-
lem is in the body controller.
CONDITION: IN DELAY MODE, WIPERS RUN CONTINUALLY WHEN WASH IS OPERATEDBUT DO NOT PROVIDE FOUR EXTRA WIPESWHEN WASH CONTROL IS RELEASED
PROCEDURE
Replace body controller.
CONDITION: WIPERS START ERRATICALLY DURING DELAY MODE
PROCEDURE
(1) Verify that the ground connection at the in-
strument panel is making a good connection, free
from paint and is tight. (2) Verify that the motor ground strap is making
good contact and that the motor mounting bolts are
tight. (3) Verify that the wiring connections to the body
controller, wiper motor, and wiper motor switch are
tight and free of corrosion. (4) If condition is not corrected, problem is with
the body controller
Ä WINDSHIELD WIPER AND WASHER SYSTEMS 8K - 13

LAMPS
CONTENTS
page page
BULB APPLICATION TABLE ............... 38
CONCEALED HEADLAMPS ................ 27
EXTERIOR LAMP SWITCHES AND HEADLAMP ALIGNMENT ........................... 3
EXTERIOR LAMP SYSTEMS .............. 25
EXTERIOR LAMPSÐAA BODY ............. 7
EXTERIOR LAMPSÐAC BODY ............ 10 EXTERIOR LAMPSÐAG BODY
............ 14
EXTERIOR LAMPSÐAJ BODY ............ 16
EXTERIOR LAMPSÐAP BODY ............ 19
EXTERIOR LAMPSÐAY-BODY ............ 22
GENERAL INFORMATION .................. 1
ILLUMINATED ENTRY SYSTEM ........... 33
GENERAL INFORMATION
Each vehicle is equipped with lamps used for illumi-
nating and indicating purposes. A circuit must have a
good ground to be complete. Circuit ground occurs
when the lamp socket makes contact with the metal
body. On vehicles with plastic lamps, a wire between
the socket and the body makes the grounds. When changing lamp bulbs, check the socket for
corrosion. If corrosion is present, clean contacts with a
wire brush and coat the inside of the socket with
Mopar tMulti-purpose Grease or equivalent.
CAUTION: Do not touch the glass of halogen bulbs
with fingers or any possibly oily surface, reduced
bulb life will result.
BODY IDENTIFICATION
Throughout this Group, references are made to the
vehicle family or body code. To decode the vehicle
identification plates, refer to the Introduction Section
at the front of this manual.
DIAGNOSTIC PROCEDURES
Begin electrical system failure diagnosis by testing
all related fuses and circuit breakers in the fuse block
and engine compartment. When a vehicle experiences problems with the head-
lamp system, verify the condition of the battery con-
nections, charging system, headlamp bulbs, wire con-
nectors, relay, high beam dimmer switch and headlamp
switch. Refer to Wiring Diagrams manual for compo-
nent locations and circuit information.
SYMPTOM
Headlamps are dim when engine is idling of
with ignition turned OFF. Canada cars must
have lamps ON. ACTION
² Clean battery terminal clamps and posts. Refer to
Group 8B, Battery/Starter/Generator Service for
proper procedures.
² Test charging system output. Refer to Group 8A,
Battery/Starting/Charging Systems Diagnostics for
proper testing procedures.
² Test for high resistance in headlamp circuits.
² Defective headlamp bulb.
SYMPTOM
Bulbs burn out frequently.
ACTION
² Test charging system output. Refer to Group 8A,
Battery/Starting/Charging Systems Diagnostics for
proper testing procedures.
² Check for loose or corroded connector terminals or
splices in headlamp circuits. Refer to Wiring Diagrams
manual for component and splice locations.
SYMPTOM
Headlamps are dim with engine running above
idle. Canada cars must have lamps ON.
ACTION
² Test charging system output. Refer to Group 8A,
Battery/Starting/Charging Systems Diagnostics for
proper testing procedures.
² Test for high resistance in headlamp circuits.
² Defective headlamp bulb.
SYMPTOM
Headlamps flash randomly.
ACTION
² Test for poor circuit ground.
² Test for high resistance in headlamp circuits.
Ä LAMPS 8L - 1

HEADLAMP TIME DELAY SYSTEM
SYSTEM OPERATION
The Body Controller controls the Headlamp Time
Delay system, if equipped. OPERATION:
By turning off the ignition switch first then off the
headlamp switch, the Body Controller will allow the
headlamps to remain ON for 60 seconds before they
automatically turn off and the headlamp doors close.
DIAGNOSIS
Refer to the Pre-diagnostic Test section of the ap-
propriate Body Diagnostic Procedures service man-
ual.
Fig. 3 Lamp Outage ModuleÐAC and AY-BodyFig. 4 Daytime Running Lamp ModuleÐCanada Only
8L - 26 LAMPS Ä

CONCEALED HEADLAMPS INDEX
page page
Concealed Headlamp MotorÐAC-Body ........ 29
Diagnostic Procedures ..................... 27
General Information ....................... 27 Headlamp DoorÐAC-Body
................. 29
Headlamp DoorÐAY Body ................. 29
Headlamp Drive MotorÐAY Body ............ 30
GENERAL INFORMATION
For proper operation of the Concealed Headlamp
System, refer to the Owner's Manual provided with
the vehicle.
The Concealed Headlamps are controlled by the Body
Controller (Fig. 1). Refer to Group 8E, Instrument
Panel for service procedures. The Body Controller re-
ceives input information from the ignition switch, head-
lamp switch, and the headlamp dimmer switch. The Body Controller also controls the headlamp doors
when the Passing Lights (manually flashing bright
lights) are used. With the headlamp switch turned off,
actuating the headlamp dimmer switch will signal the
Body Controller to open the headlamp doors. The oper-
ator then has two seconds to flash the bright lights be-
fore the Body Controller closes the headlamp doors.
Holding the headlamp dimmer switch in the engaged
position will signal the Body Controller to keep the
headlamp doors open until the dimmer switch is re-
leased. Actuating the headlamp dimmer switch with the
parking lamps ON signals the Body Controller to open
the headlamp doors and keep them open until the head-
lamp switch is turned off.
AY and AC vehicles use a single motor, centrally
located behind the radiator grille, and linked to the
headlamp doors by a torsion bar. Refer to Service
Procedures for more information. The headlamp door drive motors are equipped with
a manual override hand wheel to open or close the
headlamp doors if a failure should occur or servicing
is required. Access to the handwheel can be gained
through a flap covered hole in the sight shield be-
hind the bumper fascia, and under the hood. Several
revolutions of the handwheel may be required to
move the headlamp doors.
DIAGNOSTIC PROCEDURES
Before diagnosing a problem with the headlamp
doors, check for possible collision damage, binding,
improperly installed assemblies, or freezing weather
conditions. When diagnosing an electrical problem, refer to:
² The Concealed Headlamps Electrical Diagnosis
chart in this section.
² The Wiring Diagrams Manual.
² The Headlamp Doors System section of the appro-
priate Body Diagnostic Procedures Manual.
PROBLEM
One headlamp door is inoperative when the head-
lamp switch is ON and the ignition switch is in the
RUN position. The other headlamp door operates
normally.
AC OR AY-VEHICLE BODY CHECK:
² Headlamp door pivot and crank for seizure.
² Headlamp torsion bar sleeve or clip for excessive
wear or breakage.
² Headlamp door crank for missing or broken screw.
² Headlamp torsion bar for disengagement or break-
age.
PROBLEM
Headlamp door operates erratically.
CHECK:
² For freezing weather conditions.
² For excessive effort to move headlamp door pivots.
² For corrosion or improperly aligned components.
² For stripped motor reduction gears.
² For defective body controller. Refer to the Con-
cealed Headlamp Electrical Diagnosis chart in this
section. Also refer to the Wiring Diagrams Manual
and Body Diagnostic Procedures Manual.
Fig. 1 Body Controller
Ä LAMPS 8L - 27

ILLUMINATED ENTRY SYSTEM INDEX
page page
Body Controller ComputerÐAC, AG, AJ and AY-Body ............................. 34
Diagnostic ProceduresÐAA-Body ............ 33 Diagnostic ProceduresÐAC, AG, AJ and AY-Body . 33
General Information ....................... 33
Illuminated Entry ModuleÐAA-Body ........... 34
GENERAL INFORMATION
AA-BODY
The Illuminated Entry System (on AA Body) actu-
ates the interior courtesy and/or dome lamps (except
for the illuminated ignition switch) by lifting either
front door exterior handle. Lamp illumination is terminated 35 seconds ( 68
seconds later when battery voltage is normal), or by
turning the ignition switch to the run position,
whichever occurs first. When testing the system, all
vehicle doors must be closed to prevent the door jam
switches from activating the courtesy/dome lamps. Front door handle switches (Fig. 1), and the Illumi-
nated Entry Module (located behind and above the
glove box (Fig. 2) are used to control the system.
Depending on vehicle options, as many as six dif-
ferent electrical components/relays are located above
the glove box. The Illuminated Entry Module will be
the one mounted the closest to the outside of the in-
strument panel. The Module bracket is also used to
commonly mount the Power Door Lock Inhibitor Re-
lay, if equipped. Service procedures for door related components can
be found in Group 23, Body.
AC, AG, AJ OR AY BODY
The Illuminated Entry System (AC, AG, AJ or AY
Body) actuates the interior courtesy and/or dome lamps (except illuminated ignition switch) by lifting
either front door exterior handle. Activation can also
be accomplished with the remote keyless entry sys-
tems hand held module, if equipped. Lamp illumination is terminated 30 seconds ( 62
seconds) later, or by turning the ignition switch to
the run position, whichever occurs first. When test-
ing this system, all vehicle doors must be closed to
prevent the operation of the courtesy/dome lamps. Front door handle switches (Fig. 1), and the Body
Controller (Fig . 3 ) are used to control the system.
Service procedures for door related components can
be found in Group 23, Body.
DIAGNOSTIC PROCEDURESÐAA-BODY
For diagnostics and wiring schematics, refer to:
² The Illuminated Entry DiagnosisÐAA-Body chart
in this section.
² The Wiring Diagrams Manual.
² Fig. 4 and 5.
DIAGNOSTIC PROCEDURESÐAC, AG, AJ AND
AY-BODY
For diagnostics and wiring schematics, refer to:
Fig. 1 Illuminated Entry Door SwitchesÐTypical
Fig. 2 Illuminated Entry ModuleÐAA Body
Ä LAMPS 8L - 33

AA .............................................................................74
Low Fuel
AA ...........................................................................103
AP ............................................................................161
AC, AY...............................................................PC194
AG, AJ ............................................................5269245
Low Washer Fluid
AA, AC, AY .............................................................74
AP ............................................................................161
AG, AJ ............................................................4437661
Oil Pressure
All .......................................................................PC194
Trunk Open
AA, AC, AY .............................................................74
AP ............................................................................161
AG, AJ ............................................................4437661
Theft Alarm Set
AC, AY....................................................................168
AG, AJ ............................................................4437661
Turn Signal (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
Turn Signal (EIC)
AA, AY ..............................................................PC194
Seat Belt (MIC)
AA ...........................................................................103
AC, AG, AJ, AP, AY .......................................PC194
Seat Belt (EIC)
AA, AY ..............................................................PC194
AJ ............................................................................103
DIMMER CONTROLLED LAMPS
Service procedures for most of the lamps in the in-
strument panel, Instrument cluster and switches are
located in Group 8E, Instrument Panel and Gauges. A/C Heater Control
All ..............................................................................37
Automatic Temperature Control
All ....................................................................4437661
Column Gearshift Indicator
AA, AC, AY ...........................................................161
Console Gearshift Indicator
AP ............................................................................194
AA, AG, AJ ............................................................161
Fog Lamp Switch Symbol
AG ......................................................................PC194
Headlamp Dimmer Switch
AG, AJ ......................................................................37
Headlamp Switch Symbol
AC, AY....................................................................161
AG, AJ ......................................................................37
Heater Control
All ............................................................................158
EVIC
AJ...........................................................................ASC
Instrument Cluster (MIC)
All .......................................................................PC194
Instrument Cluster (EIC) AA, AY .....................................................................74
Message Center
AA, AC, AY .............................................................74
AP ............................................................................161
Navigator/Travel Companion
AA, AJ ......................................................................74
Radio
All ..........................................................................ASC
Rear Defogger Switch
Not Serviceable, Replace Switch
Rear Wiper Switch
AG .............................................................................37
Theft Alarm
AC, AY....................................................................161
Top Lift Switch
AJ ....................................................................5268053
Travel Computer
All ..........................................................................ASC
Turbo Gauge
AP ............................................................................161
Windshield Wiper Switch
AG, AJ ......................................................................37
NON-DIMMING LAMPS
Service procedures for most of the lamps in the fol-
lowing list can be found in Group 23, Body. Some
components have lamps that can only be serviced by
a Authorized Service Center (ASC) after the compo-
nent is removed from the vehicle. Contact local
dealer for location of nearest ASC. Ash Receiver
AA .............................................................................74
AC, AP, AY ............................................................161
AG, AJ ......................................................................37
Center Console Rear
AJ ............................................................................906
Cigar Lighter
AA, AP ....................................................................161
Courtesy
AA, AC, AY-S .....................................................214-2
AJ ............................................................................906
AY-P.....................................................................212-2
Dome
ALL ......................................................................211-2
Engine Compartment
All ............................................................................105
Glove Compartment
All ..........................................................................1891
Ignition Lock
All ..............................................................................37
Inside Rear View Mirror
AJ ............................................................................168
Overhead Console
AA ...........................................................................912
AC, AY....................................................................906
AG, AJ, AP .........................................................212-2
Reading Lamp Front
All ............................................................................906
Ä LAMPS 8L - 39

SERVICE OF DEPLOYED AIR BAG MODULE
After an air bag has been deployed, the air bag
module and clockspring must be replaced because
they cannot be reused. Other air bag system compo-
nents are replaced if damaged.
SCHEDULED MAINTENANCE INSPECTION
Vehicles equipped with a Air Bag System must be
inspected every three years or 30,000 miles / 48,000
Km. The following items should be inspected. (1) Inspect components for damage or deteriora-
tion. (a) If the air bag module housing shows signs of
physical damage or abuse, replace the module. (b) Check that both front impact sensors are
properly installed to the upper crossmember of the
radiator closure panel. Repair as required.
(2) Check the air bag warning lamp for proper op-
eration as follows: (a) Turn ignition switch to the ON position, the
air bag warning lamp should light. If not, test the system using the DRB II and Passive Restraint
System Diagnostic Procedures Manual. Repair as
required.
(b) The air bag warning lamp lights, but fails to go
out after ten seconds. Test the system using the DRB
II and Passive Restraint System Diagnostic Proce-
dures Manual. Repair as required. (c) Erasing of fault codes is not required.
AIR BAG SYSTEM CHECK
WARNING: BEFORE BEGINNING ANY AIR BAG SYS-
TEM CHECK PROCEDURES, REMOVE AND ISOLATE
THE BATTERY NEGATIVE (-) CABLE (GROUND)
FROM THE VEHICLE BATTERY. THIS IS THE ONLY
SURE WAY TO DISABLE THE AIR BAG SYSTEM.
FAILURE TO DO THIS COULD RESULT IN ACCIDEN-
TAL AIR BAG DEPLOYMENT AND POSSIBLE PER-
SONAL INJURY.
WHEN AN UNDEPLOYED AIR BAG ASSEMBLY IS
TO BE REMOVED FROM THE STEERING WHEEL,
DISCONNECT BATTERY GROUND CABLE AND
ISOLATE. ALLOW SYSTEM CAPACITOR TO DIS-
CHARGE FOR TWO MINUTES, THEN BEGIN AIR
BAG REMOVAL. (1) Disconnect the battery negative cable and iso-
late. (2) Remove forward console or cover as necessary.
(3) Connect DRB II to ASDM diagnostic 6-way con-
nector, located at right side of module. (4) Turn the ignition key to ON position. Exit vehicle
with DRB II. Use the latest version of the proper
cartridge. (5) After checking that no one is inside the vehicle,
connect the negative battery cable. (6) Using the DRB II, read and record active fault
data. (7) Read and record any stored faults.
(8) Refer to the Passive Restraint Diagnostic Test
Manual if any faults are found in steps 6 and 7. (9) Erase stored faults if there are no active fault
codes. If problems remain, fault codes will not erase. (10) With the ignition key in the ON position, make
sure no one is in the vehicle. (11) From the passenger side of vehicle, turn the
ignition key to OFF then ON and observe the instru-
ment cluster air bag lamp. It should go on for 6 to 8
seconds, then go out; indicating system is functioning
normally. If air bag warning lamp either fails to light,
blinks on and off or goes on and stays on, there is
a system malfunction. Refer to the Passive Re-
straint Diagnostic Test Manual to diagnose the
problem.
Fig. 3 Seal the Air Bag Exhaust Vents
Fig. 4 Vacuum Heater and A/C Outlets
Ä RESTRAINT SYSTEMS 8M - 3

REAR WINDOW DEFOGGER
CONTENTS
page page
CONTROL SWITCH/TIMER RELAY MODULE . . 1
GENERAL INFORMATION .................. 1REPAIR GRID LINES, TERMINALS AND PIGTAILS.3
SERVICE PROCEDURES ................... 1
GENERAL INFORMATION
For proper operation of the Rear Window Defogger
system refer to the Owner's Manual. Vehicles equipped with an electrically heated rear
window defogger also have a 40/90 amp generator. The system consists of a rear glass with two verti-
cal bus bars and a series of electrically connected
grid lines fired on the inside surface. A control
switch and a timer relay combined into a single as-
sembly is used on all models (Fig.1).
Circuit protection is provided by a fusible link, lo-
cated in the charging circuit, for the heated grid cir-
cuit and by a fuse for the relay control circuit. When the switch is turned to the ON position, cur-
rent is directed to the rear defogger grid lines. The
heated grid lines heat the rear glass to clear the sur-
face of fog or frost.
CAUTION: Grid lines can be damaged or scraped
off with sharp instruments, care should be taken in
cleaning glass or removing foreign materials, de-
cals or stickers. Normal glass cleaning solvents or
hot water used with rags or toweling is recom-
mended.
CONTROL SWITCH/TIMER RELAY MODULE
The control switch and timer relay are integrated
into a single panel or console mounted assembly. Ac-
tuating the switch energizes the circuit which allows
current to flow through the grid lines. Upon initial
actuation for approximately ten minutes, or until ei-
ther the switch or ignition is turned off. An indicat-
ing lamp illuminates a lens inlaid in the control
switch.
SERVICE PROCEDURES
Electrically heated rear window defogger operation
can be checked in vehicle in the following manner: (1) Turn ignition ON.
(2) Turn rear window defogger control switch ON.
(3) Using a ammeter on the battery. Turn the De-
fogger control switch ON, a distinct increase in am-
perage draw should be noted. (4) The rear window defogger operation can be
checked by feeling the glass. A distinct difference in
temperature between the grid lines and adjacent
clear glass can be detected in three to four minutes
of operation. (5) Using a DC voltmeter (Fig. 2) contact terminal
B with the negative lead, and terminal A with the
positive lead. The voltmeter should read 10-14 volts.
Fig. 1 Rear Window DefoggerÐTypical
Fig. 2 Rear Glass Grid Line TestÐTypical
Ä REAR WINDOW DEFOGGER 8N - 1

(6) Steps (3, 4 or 5) above will confirm system op-
eration. Indicator light illumination means that
there is power available at the output of the relay
only, and does not necessarily verify system opera-
tion. (7) If turning the switch ON produced no distinct
current draw on the ammeter the problem should be
isolated in the following manner: (a) Confirm the ignition switch is ON.
(b) Ensure that the heated rear glass feed wire is
connected to the terminal or pigtail and that the
ground wire is in fact grounded. (c) Ensure that the fusible link and control cir-
cuit fuse is operational and all electrical connec-
tions are secure.
(8) When the above steps have been completed and
the system is still inoperative, one or more of the fol-
lowing is defective: (a) Control switch/timer relay module.
(b) All rear window grid lines would have to be
broken or one of the feed wires are not connected
for the system to be inoperative.
(9) If turning the switch ON produces severe volt-
meter deflection, the circuit should be closely
checked for a shorting condition. (10) If the system operation has been verified but
indicator lamp does not light, replace the switch. (11) For detailed wiring information, refer to group
8W, Wiring Diagrams.
GRID TEST
The horizontal grid lines and vertical bus bar lines
printed and fired on inside surface of rear window
glass (Fig. 2) comprise an electrical parallel circuit.
The electrically conductive lines are composed of a
silver-ceramic material which when fired on glass be-
comes bonded to the glass and is highly resistant to
abrasion. It is possible, however, that a break may
occur in an individual grid line resulting in no cur-
rent flow through the line. To detect breaks in grid
lines the following procedure is required: (1) Turn ignition ON and turn control switch to
ON. The indicator light should come on. (2) Using a DC voltmeter with 0-15 volt range,
contact terminal B with negative lead of voltmeter.
With positive lead of voltmeter, contact terminal A
(Fig. 2). The voltmeter should read 10-14 volts. A
lower voltage reading indicates a poor ground con-
nection. (3) With negative lead of voltmeter, contact a good
body ground point. The voltage reading should not
change. (4) Connect negative lead of voltmeter to terminal
B and touch each grid line at Mid-Point with Posi-
tive lead. A reading of approximately 6 volts indi-
cates a line is good. A reading of 0 volts indicates a
break in line between Mid-Point C and terminal A.
A reading of 10-14 volts indicates a break between Mid-Point C and terminal B. Move toward break and
voltage will change as soon as break is crossed (Figs.
2 and 3).
CONTROL SWITCH/TIMER RELAY MODULE TEST
Control switch/timer relay module may be tested
in-vehicle or bench tested. In vehicle testing is ac-
complished in the following manner: (1) Remove the switch, relay assembly from the in-
strument panel or console, see Group 8E, Instrument
Panel and leave the switch connector plugged in. (2) Turn ignition ON.
(3) Using a DC voltmeter, with 0-15 range, check
voltage at terminals B, I and L. (Figs. 3 and 4). Ter-
minals B and I should confirm a voltage of 10 to 14
volts to ground when the ON switch is pressed. Ter-
minal L should confirm voltage to ground. When ter-
minals B and I show no voltage, trace circuit
upstream of switch/relay module for problem (wiring
cut, fusible link or circuit breaker inoperative, bulk-
head connector not operative, etc.) If terminal L in-
dicates voltage, place switch in Off position. If
voltage at L is still indicated or indicator lamp re-
mains on, the switch/relay module should be re-
placed. (4) If the relay checks out to this point, momen-
tarily operate switch to ON position. The indicator
lamp should come on and remain on for approxi-
mately 10 minutes. Terminal L should confirm volt-
age. If the indicator lamp fails to light or voltage at
terminal L is not confirmed the switch/relay module
should be replaced.
Fig. 3 Systems Electrical Circuit
8N - 2 REAR WINDOW DEFOGGER Ä