light CHEVROLET DYNASTY 1993 Service Manual

² If no short to ground at connector, check speaker
resistance at amplifier connector for an reading of
three to five ohms.
² If resistance is OK, refer to Radio Diagnosis. If ra-
dio checks OK, replace amplifier.
² If resistance is less than three ohms check
speaker. Check across the speaker connector if less
than three ohms replace speaker. If resistance is OK
repair wires
CONDITION: MECHANICAL NOISE DISTORTION
² Check trim for loose parts and speaker attach-
ments for buzzes
² Remove speaker still connected and listen for dis-
tortion. Distortion replace speaker.
CONDITION: ONE SPEAKER NON-OPERATIVE
² Remove output signal connector from amplifier
and check for three to five ohms resistance to the
non-operative speaker. Refer to Fig. 34 for the appro-
priate pin numbers.
² If resistance is less than three ohms, test speaker
for resistance.
² If OK repair wire. If not replace speaker.
CONDITION: ALL SPEAKERS NON-OPERATIVE
²Check radio for being ON, are the display lights
on
² Radio not ON, refer to Radio Diagnosis
² Check Amplifier Connectors and wires for proper
connection
² Check pin 9 and pin 27 for battery voltage
² If voltage OK replace amplifier ²
If pin 27 has battery voltage and pin 9 has 0 volt-
age. Refer to Power Antenna Diagnosis and test volt-
age at antenna relay.
² If pin 9 has battery voltage and pin 27 has 0 volt-
age. Check pin 27 for short to ground.
² If shorted to ground repair wire
² If no short to ground check fuse cavity number 16
for blown fuse.
² If fuse blows again replace amplifier
RELAY/CHOKEÐINFINITY SPEAKER
If the audio system is lacking bass, check for con-
tinuity across the relay and choke connectors. If no
continuity, replace relay/choke assembly (Fig. 35).
LOCATION
(1) AA and AP Bodies, attached to the reinforce-
ment above glove box. (2) AG Body, attached to the dimmer module bay-
onet bracket on the bulkhead behind the glove box.
Fig. 35 Relay/Choke Assembly
Ä AUDIO SYSTEM 8F - 29

HORNS
CONTENTS
page page
GENERAL INFORMATION .................. 1
HORN SWITCH REPLACEMENT ............ 3 TESTING HORN SYSTEM
................. 1
GENERAL INFORMATION
WARNING: ON VEHICLES EQUIPPED WITH AIR
BAG, SEE GROUP 8M, RESTRAINT SYSTEMS FOR
STEERING WHEEL OR COLUMN REMOVAL PROCE-
DURES.
The horn circuit consists of a horn switch, horn re-
lay, and horns. The horn circuit feed is from the fuse
box to the number 1 terminal on the horn relay.
When the horn switch is depressed, this completes
the circuit to ground. This activates the horn relay
and an set of contacts in the relay to close, which al-
lows current to flow to the horn(s). The horn ground
wire is attached to the headlamp ground screw (Fig.
1).
TESTING HORN SYSTEM
HORNS WILL NOT SOUND
If the horns do not sound, check for a blown horn
fuse in the fuse block. If the fuse is blown, replace it
with the same fuse type. If the horns fail to sound
and the new fuse blows when depressing the horn
switch, a short circuit in the horn or the horn wiring
between the fuse terminal and the horn is responsi-
ble. If the fuse is good, disconnect wire connector at
horn. Using an test lamp, connect one lead to the
negative terminal and the other to the positive ter-
minal (Fig. 2). Depress the horn switch, the test
lamp should illuminate. If not connect the test lamp wire to a good ground and depress the horn switch. If
test lamp lights inspect ground wire circuit and re-
pair as needed.
If the test lamp fails to illuminate, check for a de-
fective horn relay. Substituting a known good horn
relay in the circuit. If the test lamp illuminates
when depressing the horn switch, the original relay
is defective. If the test lamp fails to illuminate with
a known good relay, unplug that relay. Connect a
jumper wire from the battery terminal to the horn
terminal on the relay terminal board (Fig. 3, 4, or 5).
If the test lamp connected in place of the horns, fails
to illuminate an open circuit in the wiring between
the relay terminal and the horn switch is at fault re-
pair as necessary.
HORNS SOUND CONTINUOUSLY
CAUTION: Continuous sounding of horns may
cause relay to fail.
Should the horns sound continuously, unplug the
horn relay from the terminal board inside the pas-
senger compartment. Plug in a known good relay. If
the horns stop blowing, relay is defective and must
be replaced. Should the horns still sound, proceed as
follows: Connect one voltmeter lead to battery termi-
nal on relay board and the other lead to switch ter-
minal. Refer to Figs. 6, 7, or 8. Voltmeter will
Fig. 1 Conventional Horn System
Fig. 2 Horn and Connector
Ä HORNS 8G - 1

INOPERATIVE SYSTEM
If road test verifies an inoperative system with a
correct speedometer operation:
² Inspect fuse
² Check for loose electrical and vacuum connections
at the servo
² Check for correct position of the vacuum check
valve in the hose from servo to vacuum source. The
word VAC on the valve must point toward the vac-
uum source.
² Inspection should also be made to verify that both
ends of the vehicle speed control cable are securely
attached. If either end is loose, the vehicle speed con-
trol will be inoperative.
CHECKING FOR FAULT CODE
(1) When trying to verify a vehicle speed control
electronic malfunction: (a) Connect a DRB II if available.
(b) Plug DRB II into the diagnostic connector in
the engine compartment. (c) Check that either a Fault Code 34 or Fault
Code 15 is indicated. (d) An inoperative vehicle speed control may still
occur without either fault code being indicated. (e) With key inserted in ignition switch, cycle
switch to ON position three times. On third cycle,
leave switch in ON position. (f) After switch has been cycled three times, ob-
serve CHECK ENGINE indicator on instrument
cluster. If a Fault Code is present, indicator will
flash (blink) in a series which will show which
Fault Code is the problem. EXAMPLE: A series of
three flashes in rapid succession, a slight pause,
then four flashes in rapid succession would indicate
Fault Code 34.
(2) If no Fault Code appears, or Fault Code 34 is
observed, refer to:
² The Servo Electrical Test.
² The Powertrain Control Module Electrical Test.
(3) If a fault code 15 is observed, test vehicle speed
sensor. For testing vehicle speed sensor and related compo-
nents refer to the Powertrain Diagnostics Test Proce-
dure Manual. (4) Correct any problems found when performing
these tests and recheck for Fault Code if changes
were made. (5) If no problems were found above, replace pow-
ertrain control module.
VEHICLE SPEED CONTROL ELECTRICAL TESTS
WARNING: IF REMOVAL OF AIR BAG MODULE IS
NECESSARY, REFER TO GROUP 8M, RESTRAINT
SYSTEMS.
Fig. 6 Vehicle Speed ControlÐAC & AY Bodies with 2.5L
Ä VEHICLE SPEED CONTROL 8H - 3

CONDITION: MOTOR RUNS SLOWLY AT ALL SPEEDS
PROCEDURE
(1) Disconnect wiring harness connector at motor.
Remove wiper arms and blades. Connect an ammeter
between battery (B+) and terminal 3 on motor (Fig.
11).
(a) If motor runs and average ammeter reading
is more than 6 amps, proceed to step 2. (b) If motor runs and average ammeter reading
is less than 6 amps, proceed to step 3.
(2) Check to see if wiper linkage or pivots are
binding or caught. Disconnect drive link from motor. (a) If motor now runs and draws less than 3
amps, repair linkage system. (b) If motor continues to draw more than 3 amps,
replace motor assembly.
(3) Check motor wiring harness for shorting be-
tween high and low speed wires as follows: (a) Connect a voltmeter or test lamp to motor
ground strap. (b) Set wiper switch to LOW position.
(c) Connect other lead of voltmeter to terminal 4
of the wiring harness. (d) If voltage is present, there is a short in the
wiring or wiper switch. If no voltage is present pro-
ceed to step e. (e) Set wiper switch to HIGH position.
(f) Move voltmeter lead from terminal 4 to termi-
nal 3 of the wiring harness. (g) If voltage is present, there is a short in the
wiring or wiper switch.
CONDITION: MOTOR WILL RUN AT HIGH SPEED, BUT NOT AT LOW SPEED. MOTORWILL RUN AT LOW SPEED, BUT NOT AT HIGHSPEED
PROCEDURE
(1) If motor will not run on high speed, put switch
in HIGH position and connect a test lamp between
motor Terminal 4 and ground (Fig. 12).
(2) If motor will not run on low speed, put switch
in LOW position and connect a test lamp between
motor Terminal 3 and ground. (3) If test lamp does not light at motor terminal,
there is an open in wiring or switch. If test lamp
lights at motor terminal, replace motor assembly.
CONDITION: MOTOR WILL KEEP RUNNING WITH SWITCH IN OFF POSITION
PROCEDURE
Remove wiring harness. Connect jumper from Ter-
minal 1 to Terminal 3 of wiper motor (Fig. 13). Con-
nect second jumper from Terminal 2 to battery (B+).
If motor runs to PARK position and stops, wiper
switch is faulty. If motor keeps running and does not
park, replace motor assembly.
Fig. 10 Voltmeter Between Terminal 3 and Ground
Fig. 11 Ammeter Between Terminal 3 and Battery
Fig. 12 Test Lamp Between Terminal 4 and Ground
Ä WINDSHIELD WIPER AND WASHER SYSTEMS 8K - 5

INSTALLATION
Reverse the preceding operation.
TAIL, STOP AND TURN SIGNAL AND BACK-UP
LAMP
REMOVAL (FIG. 4)
(1) Open deck lid and remove the plastic wing nut
securing the rear trim cover in place. (2) Pivot the end of the trim panel out of the way
to gain access, and remove wing-nuts holding the
lamp to the vehicle. (3) Separate the tail lamp from the body far
enough to rotate the socket and bulb assemblies. Ro-
tate sockets one-half turn and pull the sockets out of
the lamp body. (4) Remove the bulb from the socket.
INSTALLATION
Reverse the preceding operation.
LICENSE PLATE LAMPSÐAA/C Body
REMOVAL (FIG. 5)
(1) Remove screws holding license plate lamp to
rear bumper fascia. (2) Separate license plate lamp from fascia.
(3) Remove socket from license plate lamp.
(4) Pull bulb from socket if bulb replacement is re-
quired.
INSTALLATION
Reverse the preceding operation.
LICENSE PLATE LAMP OR BULBÐAA/P Body
REMOVAL (FIG. 6)
(1) Remove two lamp assembly attaching screws
above the rear license plate opening. (2) Remove the lens from the deck-lid.
(3) Pull the bulb from the socket.
INSTALLATION
Reverse the preceding operation.
Fig. 3 Front Side Marker Lamps
Fig. 4 Rear LightingÐAA/P or AA/D Body
Fig. 5 License Plate LampsÐAA/C Body
Fig. 6 License Plate LampÐAA/P Body
8L - 8 LAMPS Ä

EXTERIOR LAMPSÐAC BODY INDEX
page page
Aero Headlamp Bulb ...................... 10
Aero Headlamp Housing ................... 11
Aero HeadlampsÐAC/D-Body ............... 10
Center High Mounted Stop Lamp (CHMSL) ..... 13
Center High-Mounted Stop Lamp (CHMSL) Bulb . 13
Cornering Lamp Assembly .................. 12
Cornering Lamp Bulb ..................... 12
Front Side Marker BulbÐAC/C-Body .......... 12
Front Side Marker LampÐAC/C-Body ......... 12
Headlamp Diagnosis ...................... 10 Headlamp Sealed BeamÐAC/C Body
......... 10
License Plate Lamp/Bulb ................... 13
Park/Turn Signal Lamp or BulbÐAC/C-Body .... 11
Park/Turn Signal Lamp or BulbÐAC/D-Body .... 11
Rear Side Marker Lamp BulbÐAC/C-Body ..... 13
Rear Side Marker LampÐAC/C-Body ......... 13
Tail, Stop, Turn Signal, Back-Up and Side Marker LampÐAC/D-Body ...................... 12
Tail, Stop, Turn Signal, Back-Up LampÐAC/C or AY/S-Body ............................ 12
HEADLAMP DIAGNOSIS
Refer to the Headlamp Diagnosis at the beginning of
this Group. Refer to Wiring Diagrams Manual for
circuit and component locations.
HEADLAMP SEALED BEAMÐAC/C BODY
REMOVAL
(1) Turn the headlight switch ON.
(2) Open the hood and locate the Power Distribution
Center forward of the left front suspension tower (Fig.
1). Remove the cover. (3) Remove the Headlamp Close Relay (Fig. 2) to
prevent the headlamp doors from closing. (4) Turn the headlight switch OFF.
(5) Remove screws from headlamp bezel and remove
bezel, if equipped. (6) Remove screws from interior retaining ring (Fig.
3), and remove ring. Do not disturb the headlamp adjusting screws.
(7) Pull out sealed beam unit and unplug connector.
INSTALLATION
Reverse the preceding operation.
AERO HEADLAMPSÐAC/D-BODY
Lens fogging is a normal condition and does
not require service, as moisture will vent from
tubes behind the lens.
AERO HEADLAMP BULB
REMOVAL (FIG. 4)
(1) Locate and remove the wire connector behind the
headlamp assembly in the engine compartment.
CAUTION: Do not touch the bulb with fingers or any
possibly oily surface, reduced bulb life will result. (2) Rotate the bulb retaining ring counterclockwise
one quarter turn and remove the ring, bulb and bulb
holder from the lens assembly. The bulb holder has
alignment notches.
INSTALLATION
Reverse the preceding operation.
Fig. 1 Power Distribution Center
Fig. 2 Headlamp Close Relay
8L - 10 LAMPS Ä

(3) Separate the lamp assembly from the rear clo-
sure panel. (4) Rotate the socket and bulb assemblies counter-
clockwise and pull the sockets from the lamp. (5) Remove the bulbs from the sockets.
INSTALLATION
Reverse the preceding operation.
REAR SIDE MARKER LAMP BULBÐAC/C-BODY
REMOVAL (FIG. 8)
(1) Raise the deck lid and roll the trunk liner
away from the inner quarter panel. (2) Rotate the socket and bulb assembly counter-
clockwise and pull the socket from the lamp. (3) Remove the bulb from the socket.
INSTALLATION
Reverse the preceding operation.
REAR SIDE MARKER LAMPÐAC/C-BODY
REMOVAL (FIG. 8)
(1) Remove the body side molding. Refer to Group
23, Body. (2) Remove socket assembly and attaching nuts
and separate lamp from the body.
INSTALLATION
Reverse the preceding operation.
LICENSE PLATE LAMP/BULB
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 (CHMSL)
BULB
REMOVAL
(1) Open trunk 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 (CHMSL)
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. 9 Rear LightingÐAC/D-Body
Fig. 10 CHMSL
Ä LAMPS 8L - 13

EXTERIOR LAMPSÐAY-BODY INDEX
page page
Center High Mounted Stop Lamp ............ 24
Center High Mounted Stop Lamp Bulb (CHMSL) . 24
Cornering Lamp or BulbÐAY/C-P-Body ........ 24
Front Side Marker BulbÐAY/C-P-Body ........ 23
Front Side Marker LampÐAY/C-P-Body ....... 23
General Information ....................... 22
Headlamp Diagnosis ...................... 22 Headlamps
............................. 22
License Plate Lamp or BulbÐAY/C-P-Body ..... 24
Park, Turn Signal Lamp or BulbÐAY/C-P-Body . . 22
Sealed Beam ........................... 22
Tail, Stop, Turn Signal, Side Marker and Back-Up Lamp or BulbÐAY/C-P-Body .............. 24
GENERAL INFORMATION
To service exterior lamps on AY/C-S-Body, refer to
procedures covered in Exterior LampsÐAC-Body sec-
tion. AC/C-S-Body uses the same lamps as AY/C-S-
Body.
HEADLAMPS
Conventional and halogen sealed beams are inter-
changeable, It is not recommended that they be
mixed. The lens, filament and reflector of sealed
beams are molded into one unit.
HEADLAMP DIAGNOSIS
For headlamp diagnosis, refer to the headlamp di-
agnosis chart at the beginning of this Group. Refer to
Wiring Diagrams manual for circuit and component
locations.
SEALED BEAM
REMOVAL
(1) Turn the headlight switch ON.
(2) Open the hood and locate the power distribu-
tion center forward of the left front suspension tower
(Fig. 1). Remove the cover. (3) Remove the headlamp close relay (Fig. 2) to
prevent the headlamp doors from closing. (4) Turn the headlight switch OFF.
(5) Remove screws from headlamp bezel and re-
move bezel, if equipped. Do not disturb the headlamp adjusting screws.
(6) Remove screws from interior retaining ring
(Fig. 3), and remove ring. (7) Separate sealed beam from seat and disconnect
wire connector.
INSTALLATION
Reverse the preceding operation.
PARK, TURN SIGNAL LAMP OR BULBÐAY/C-P-
BODY
REMOVAL
(1) Open the headlamp doors. (2) Remove push-in fasteners holding lower park
and turn signal lamp shield to grille opening panel
(Fig. 4). (3) Remove screws holding park and turn signal
lamp grille opening panel (Fig. 5). (4) Remove sockets from lamp and pull bulbs from
sockets if bulbs replacement is required (Fig. 6).
Fig. 1 Power Distribution Center
Fig. 2 Headlamp Close Relay
8L - 22 LAMPS Ä

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

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