1993 CHEVROLET DYNASTY service

AG AND AJ BODIES INDEX
page page
Cigar Lighter Removal ..................... 55
Cluster and Gauge Service and Testing ....... 43
Electronic Cluster ........................ 50
Electronic Vehicle Information Center (EVIC) .... 42
Engine Compartment Node ................. 55
Gauges ................................ 44 General Information
....................... 42
Instrument Panel Roll Down Procedure ........ 56
Interior Lamp Removal .................... 57
Mechanical/Electronic Cluster Removal ........ 43
Switch and Panel Component Service ......... 51
Switch Pod Assembly Removal .............. 43
GENERAL INFORMATION
CONVENTIONAL INSTRUMENT CLUSTER
The conventional instrument cluster incorporates
magnetic type gauges (Fig. 1).
The readings are only accurate when the ignition
switch is in the ON position.
TACHOMETER DRIVE MODULE
The tachometer drive module is an electronic mod-
ule used to drive a magnetic tachometer in a conven-
tional instrument cluster.
MESSAGE CENTER
The message center provides the driver with infor-
mation in addition to the standard vehicle instru-
mentation. A bezel will light up with door ajar,
washer fluid, deck ajar and alarm set information.
For vehicles without message center a plain bezel is
used.
ELECTRONIC VEHICLE INFORMATION CENTER
(EVIC)
The Electronic Vehicle Information Center is a
computer controlled warning system which, monitors
various sensors used on the vehicle. The system sup-
plements the warning indicators in the instrument
cluster. Visual warning messages are displayed by a
digital display (Fig. 2). Refer to Group 8C, Overhead
Console.
ELECTRONIC INSTRUMENT CLUSTER
The electronic instrument cluster uses vacuum flu-
orescent displays to display:
² Oil pressure
² System voltage
² Engine temperature
² Fuel level
² Speedometer and tachometer readings as well as
all warning indicators. The electronic cluster is eas-
ily distinguished from the conventional cluster by its
digital and linear display (Fig. 3.
ELECTRONIC CLUSTER DIMMING
The electronic cluster display is dimmed from day-
time to nighttime intensity when the head]lamp
switch is turned on. This intensity can be controlled
using the headlamp switch sliding rheostat. An additional detent on the headlamp switch rheo-
stat will allow daytime intensity while driving with
headlamps ON in daytime.
Fig. 1 Conventional Instrument Cluster
Fig. 2 EVIC
Fig. 3 Electronic Instrument Cluster
8E - 42 INSTRUMENT PANEL AND GAUGES Ä

ELECTRONIC DIGITAL CLOCK
The electronic digital clock is in the radio. The
clock and radio each use the display panel built into
the radio. A digital readout indicates the time in
hours and minutes whenever the ignition switch is in
the ON or ACC position. When the ignition switch is in the ON or OFF po-
sition, or when the radio frequency is being dis-
played, time keeping is accurately maintained. The procedure for setting the clock varies slightly
with each radio. The correct procedure is described
under the individual radio operating instructions re-
ferred to in the Owner's manual supplied with the
vehicle.
WARNING LAMPS
The AG & AJ Body instrument clusters have warn-
ing lamps or indicators with the electronic cluster for
six different systems. These include low oil pressure,
check gauges, brake system, air bag, seat belt, mal-
function indicator (check engine) lamp.
CLUSTER AND GAUGE SERVICE AND TESTING
CAUTION: Disconnect negative battery cable, in en-
gine compartment, before servicing instrument
panel. When power is required for test purposes,
reconnect battery cable for test only. Disconnect negative battery cable after test and be-
fore continuing service procedures. It is not necessary to remove instrument cluster
from vehicle for gauge replacement. Gauges must be pulled straight out, when remov-
ing or pins may be damaged.
SWITCH POD ASSEMBLY REMOVAL
(1) Disconnect negative battery cable.
(2) Pry up edge of panel vent grille, using a
straight flat edge tool to disengage clips, then re-
move grille (Fig. 4). (3) Remove two screws located under panel vent
grille. (4) Remove two screws underneath switch POD as-
sembly. (5) With tilt steering adjust steering wheel to the
lowest setting. (6) Pull switch module rearward to remove module
and disconnect all wire connections. (7) For Installation reverse above procedures.
Tighten all screws to 2 N Im (20 in. lbs.) torque.
MECHANICAL/ELECTRONIC CLUSTER REMOVAL
CLUSTER MASK AND LENS REMOVAL
(1) Remove switch pod assembly (Fig. 4).
(2) Remove tilt column lever if equipped.
(3) Remove steering column trim cover.
Fig. 4 Switch POD Assembly
Ä INSTRUMENT PANEL AND GAUGES 8E - 43

(3) With the ignition switch ON, an open (discon-
nected sending unit wire) causes the oil, fuel or tem-
perature gauge to read below low, empty or cold
indicators. (4) If steps 2 and 3 check OK, refer to the individ-
ual sending unit test procedures.
FUEL TANK SENDING UNIT TEST
Refer to Group 14, Fuel for test procedure.
CHECK GAUGES WARNING LAMP TESTS
The check gauges warning lamp will illuminated
when the ignition key is turned to the ON position.
The lamp will illuminate if the engine oil pressure
drops below a safe level. The check gauge lamp will
light for high engine temperature or for low voltage. To test the system turn ignition key to the ON po-
sition. If the lamp fails to light, inspect for a broken
or disconnected wire at the oil pressure combination
sending unit, which is located at the front of the en-
gine (Fig. 13). If the wire at the connector checks
good pull connector loose from the switch terminal
and with a jumper wire ground connector to the en-
gine. With the ignition key turned to the ON posi-
tion check the warning lamp. If lamp still fails to
light, inspect for a burned lamp. If lamp still fails to
light, inspect for a burned out lamp or disconnected
socket in the cluster.
To test the switch disconnect the switch electrical
connector. Attach positive lead of an ohmmeter to
the switch terminal for the gray (GY) wire and the
negative lead to an engine ground. With the engine
off, there should be continuity in the system. Start
the engine. With the engine running, the ohmmeter
should show no continuity. If the above results are
not obtained, replace the switch.
COMBINATION OIL SENDING UNIT TEST
The combination oil sending unit has two func-
tions: (1) The normal closed circuit keeps the oil pressure
warning lamp on until there is oil pressure. (2) The sending unit provides a resistance that
varies with oil pressure. To test the normally closed oil lamp circuit, discon-
nect the locking connector and measure the resis-
tance between the switch terminal and the metal
housing. The ohmmeter should read 0 ohms. Start
the engine (Fig. 14).
If there is oil pressure, the ohmmeter should read
an open circuit. To test the sending unit, measure the resistance
between the sending unit terminal and the metal
housing. The ohmmeter should read open. Start the
engine. The ohmmeter should read between 30 to 55 ohms,
depending on engine speed, oil temperature, and oil
viscosity. If the above results are not obtained, replace the
sending unit.
SEAT BELT WARNING SYSTEM
For testing of this system refer to Group 8U,
Chime Warning/Reminder System.
MALFUNCTION INDICATOR (CHECK ENGINE) SYSTEM
For testing this system refer to the Body Diagnos-
tic Procedures booklet.
BRAKE SYSTEM WARNING LAMP TEST
The brake warning lamp illuminates when parking
brake is applied with ignition key turned ON. The
same lamp will also illuminate should one of the two
service brake systems fail when brake pedal is ap-
plied. To test system turn ignition key ON, and ap-
ply parking brake. If lamp fails to light, inspect for a
burned out lamp, disconnected socket, a broken or
disconnected wire at switch. The lamp also lights
when the ignition switch is turned to START. Refer
to Brake System Warning Lamp Diagnosis Chart
(Fig. 15). To test service brake warning system, raise vehicle
on a hoist and open a wheel cylinder bleeder while aFig. 13 Combination Oil Sending Unit
Fig. 14 Combination Oil Sending Unit Test
Ä INSTRUMENT PANEL AND GAUGES 8E - 47

helper depresses brake pedal and observes warning
lamp. If lamp fails to light, inspect for a burned out
lamp, disconnected socket, a broken or disconnected
wire at switch.If lamp is not burned out and wire continuity is
proven, replace brake warning switch in brake line
TEE fitting mounted on frame rail in engine com-
partment below master cylinder (Fig.16).
CAUTION: If wheel cylinder bleeder was opened
check master cylinder fluid level.
SPEEDOMETER SYSTEM
The vehicles are equipped with electronically
driven speedometer and odometer assemblies. The
unit has the same appearance as a conventional
speedometer but it eliminates the cable-driven me-
chanical system. A signal is sent from a transmis-
sion-mounted vehicle speed sensor to the
speedometer circuitry through the wiring harness.
By eliminating the speedometer cable, instrument
cluster service and removal is improved. Refer to Fig.
17 Speedometer Diagnosis Chart. When the speedometer is out of calibration. The
electronic automatic transaxle vehicle speed sensor
output must be calibrated to reflect the different combinations of equipment. The procedure is called
Pinion Factor, refer to Group 21, Transaxle for the
procedure.
Fig. 15 Brake System Warning Lamp Diagnosis
Fig. 16 Brake Warning Lamp Switch
8E - 48 INSTRUMENT PANEL AND GAUGES Ä

Perform cluster Self Diagnostic Test to determine
whether problem is within cluster or outside of clus-
ter. Refer to Fig. 24 and 25.
Successful completion of the SELF DIAGNOSTIC
TEST indicates that the problem is in the wiring,
connectors or sensors out side of the cluster.
CLUSTER ASSEMBLY REMOVAL
The electronic cluster which is serviced as an as-
sembly is removed with the same procedure as the
conventional cluster.
CONDITION: CLUSTER DISPLAYS DO NOT ILLUMINATE AFTER VEHICLE IS STARTED
(1) Check fuses and verify battery and ignition
voltage at cluster connector. (2) Check ground from cluster connector to instru-
ment panel ground stud.
SWITCH AND PANEL COMPONENT SERVICE
HEADLAMP SWITCH
The headlamp switch is located on the left side of
the switch pod. The switch controls the headlamps,
parking lamps, fog lamps and instrument light dim- ming. If any of the switches require replacement the
entire headlamp switch assembly must be replaced
(Fig. 26 and 27).
REMOVAL
(1) Remove switch pod assembly from the instru-
ment panel. DO NOT attempt to remove instrument
cluster dimmer switch or wiper delay switch knob,
they are not removable. (2) Remove turn signal switch lever by pulling
straight out of switch pod. (3) Remove screws from bottom of switch pod.
(4) Separate inner and outer switch pod halves and
remove turn signal switch to gain access to screw. (5) Remove five inner switch pod panel screws and
3 screws from underneath the switch pod. Separate
the inner bezel from the outer bezel. (6) Remove switch mounting screws before discon-
necting linkage. (7) Disconnect switch linkage from buttons. Pull
the linkage straight up from the switch/button to dis-
engage it and remove switch.
Fig. 23 Mechanical Cluster Lamp Location
Ä INSTRUMENT PANEL AND GAUGES 8E - 51

AP BODY INDEX
page page
Cluster and Gauge Service and Testing ....... 58
Gauges ................................ 61
General Information ....................... 58 Instrument Panel Replacement
.............. 72
Interior Lamp Replacement ................. 73
Switch and Panel Component Service ......... 67
GENERAL INFORMATION
INSTRUMENT CLUSTER
There are two conventional instrument cluster as-
semblies available. The clusters incorporates mag-
netic type gauges and an electronically driven
speedometer and odometer assembly (Fig. 1 and 2).
MAGNETIC GAUGES
All gauges on the AP Body clusters are the mag-
netic type gauges. When the ignition switch is in the
OFF position each gauge, except for the voltmeter
and tachometer will show a reading. However, the
readings are only accurate when the ignition switch
is in the ON position.
TACHOMETER DRIVE MODULE
The tachometer drive module is an electronic mod-
ule used to drive the magnetic tachometer in the
high line cluster. This module is located on top of the instrument
cluster.
ELECTRONIC DIGITAL CLOCK
The electronic digital clock is in the radio. The
clock and radio each use the display panel built into
the radio. A digital readout indicates the time in
hours and minutes whenever the ignition switch is in
the ON or ACC position. When the ignition switch is in the OFF position, or
when the radio frequency is being displayed, time
keeping is accurately maintained. The procedure for setting the clock varies slightly
with each radio. The correct procedure is described
under the individual radio operating instructions re-
fer to the Sound Systems Manual supplied with the
vehicle.
WARNING LAMPS AND INDICATOR LIGHTS
The instrument cluster has warning and indicators
lamps for eight different systems:
² Low oil pressure
² Brake warning
² Seat belt warning
² Malfunction indicator (check engine) lamp
² Air Bag
² High beam indicator
² Right and left turn signals.
² Anti-lock (ABS)
CLUSTER AND GAUGE SERVICE AND TESTING
CAUTION: Disconnect the negative battery cable
before servicing the instrument panel. When power
is required for test purposes, reconnect battery ca-
ble for test only. Disconnect the negative battery
cable after test and before continuing service pro-
cedures.
SENDING UNIT TEST
Check for a defective sending unit or wiring, when
a problem occurs with a cluster gauge. Do this before
disassembling the cluster. (1) Sending units and wiring can be checked by
grounding the connector leads, at the sending unit,
in the vehicle. (2) With the ignition in the ON position, a
grounded input will cause the fuel or temperature
gauge to read at or above maximum.
Fig. 1 Instrument Cluster With Tachometer
Fig. 2 Instrument Cluster Without Tachometer
8E - 58 INSTRUMENT PANEL AND GAUGES Ä

FUEL TANK SENDING UNIT TEST
Refer to Group 14, Fuel for test procedures.
LOW OIL PRESSURE WARNING LAMP TEST
The low oil pressure warning lamp will illuminate
when the ignition key is turned to the ON position
without engine running. The lamp also illuminates
should the engine oil pressure drop below a safe oil
pressure level. To test the system turn ignition key to the ON po-
sition. If the lamp fails to light, inspect for a broken
or disconnected wire at the oil pressure combination
unit, located at the front of the engine (Fig. 3). If the
wire at the connector checks good, pull connector
loose from the switch and with a jumper wire ground
connector to the engine. With the ignition key turned
to the ON position check the warning lamp. If lamp
still fails to light, inspect for a burned out lamp or
disconnected socket in the cluster.
COMBINATION OIL SENDING UNIT TEST
The combination oil sending unit has two func-
tions: (1) The normal closed circuit keeps the oil pressure
warning lamp on until there is oil pressure (Fig. 4).
(2) The sending unit provides a resistance that
varies with oil pressure. To test the normally closed oil lamp circuit, discon-
nect the locking connector and measure the resis-
tance between the switch terminal and the metal
housing. The ohmmeter should read continuity. Start
the engine. If there is oil pressure, the ohmmeter should read
an open circuit. To test the sending unit, measure the resistance
between the sending unit terminal and the metal
housing. The ohmmeter should no continuity. Start
the engine. The ohmmeter should read between 30 to 55 ohms,
depending on engine speed, oil temperature and oil
viscosity. If the above results are not obtained, replace the
sending unit.
SEAT BELT WARNING SYSTEM
For testing of this system refer to Group 8M, Re-
straint Systems.
AIR BAG WARNING SYSTEM
For testing of this system refer to Group 8M, Re-
straint Systems.
MALFUNCTION INDICATOR (CHECK ENGINE) SYSTEM
For testing of this system using DRB II, refer to
the Body Powertrain Diagnostic Procedures.
BRAKE SYSTEM WARNING LAMP TEST
The brake warning lamp illuminates when parking
brake is applied with ignition key turned ON. The
same lamp will also illuminate should one of the two
service brake systems fail when brake pedal is ap-
plied. Refer to Brake system warning Lamp Diagno-
sis (Fig. 5). To test system turn ignition key ON and apply
parking brake. If lamp fails to light, inspect for a
burned out lamp, disconnected socket, a broken or
disconnected wire at switch. The lamp also lights
when the ignition switch is turned to start. To test service brake warning system, raise vehicle
on a hoist and open a wheel cylinder bleeder while a
helper depresses brake pedal and observes warning
lamp. If lamp fails to light, inspect for a burned out
lamp, disconnected socket, a broken or disconnected
wire at switch. If lamp is not burned out and wire continuity is
proven, replace brake warning switch in brake line
Tee fitting mounted on frame rail in engine compart-
ment below master cylinder (Fig. 6).
CAUTION: If wheel cylinder bleeder was opened
check master cylinder fluid level.
Fig. 3 Combination Oil Sending Unit
Fig. 4 Combination Oil Sending Unit Test
Ä INSTRUMENT PANEL AND GAUGES 8E - 59

ment cluster and pin 43 of the powertrain control
module connector, replace the powertrain control
module. (8) If all tests performed test good replace the ta-
chometer drive module. (9) If the tachometer continues to be inoperative,
replace the tachometer assembly.
TACHOMETER DRIVE MODULE REPLACEMENT
(1) Remove instrument cluster (Fig. 13).
(2) Remove drive module by pivoting upward from
printed circuit board and pulling away from locating
notches. (3) For installation, position module on locating
notches and push down securely over printed circuit
board and reverse above procedures.
SPEEDOMETER SYSTEM
AP-body vehicles are equipped with electronically
driven speedometer and odometer assemblies. The
unit has the same appearance as a conventional
speedometer but it eliminates the cable-driven me-
chanical system. A signal is sent from a transmis- sion-mounted speed sensor to the speedometer
circuitry through the wiring harness. By eliminating
the speedometer cable, instrument cluster service
and removal is improved. Refer to Fig. 14 Speedom-
eter Diagnosis.
When the speedometer is out of calibration. The
electronic automatic transaxle vehicle speed sensor
output must be calibrated to reflect the different
combinations of equipment. The procedure is called
Pinion Factor, refer to Group 21, Transaxle for the
procedure.
SPEEDOMETER/ODOMETER ASSEMBLY REPLACEMENT
(1) Remove cluster bezel.
(2) Remove cluster mask and lens.
(3) Remove tachometer. If equipped.
(4) Remove fuel gauge.
(5) Remove three screws attaching speedometer/
odometer assembly to the cluster housing. (6) Pull speedometer rearward to remove from
cluster housing. (7) For installation reverse above procedures.
VEHICLE SPEED SENSOR REPLACEMENT
(1) Remove harness connector from sensor and
make sure weather seal is on harness connector. (2) Remove sensor retaining bolt.
(3) Pull sensor and pinion gear assembly out of
transaxle. If necessary, carefully pry loose with a flat
blade screwdriver (Fig. 15 and 16). (4) For installation reverse above procedures and
seat sensor assembly by hand to insure proper gear
engagement. Tighten retaining bolt to 7 N Im (60 in.
lbs.) torque.
ELECTRONIC AUTOMATIC TRANSAXLE VEHICLE SPEED SENSOR REPLACEMENT
The output vehicle speed sensor is located to the
left of the manual shift lever. (1) Raise and support vehicle on safety stands.
(2) Remove vehicle speed sensor (Fig. 17).
(3) For installation, reverse above procedures.
Fig. 12 Powertrain Control Module Pin Location
Fig. 13 Tachometer Drive Module
Ä INSTRUMENT PANEL AND GAUGES 8E - 65