light CHEVROLET DYNASTY 1993 Owners Manual

The coil's low primary resistance allows the PCM to
fully charge the coil for each firing.
COOLANT TEMPERATURE SENSOR
On 2.2L Turbo III engines, the coolant temperature
sensor is installed into the thermostat housing (Fig. 30).
On 3.3L and 3.8L engines, the coolant temperature sensor
is located next to the thermostat housing (Fig. 31).
The coolant temperature sensor provides an input
voltage to the powertrain control module (PCM). The
sensor is a variable resistance (thermistor) with a
range of -40ÉC to 130ÉC (-40ÉF to 265ÉF). As coolant
temperature varies, the sensor resistance changes,
resulting in a different input voltage to the PCM.
The PCM contains different spark advance schedules
for cold and warm engine operation. The schedules reduce
engine emission and improve driveability.
The PCM demands slightly richer air-fuel mixtures
and higher idle speeds until the engine reaches normal
operating temperature. The coolant sensor input is also used for cooling
fan control.
KNOCK SENSORÐTURBO III ENGINE
Turbo III engines use a knock sensor. The sensor gen-
erates a signal when spark detonation occurs in the
combustion chambers. The sensor is mounted on the in-
take manifold behind the PCV breather (Fig. 32). The
sensor provides input voltage used by the powertrain
control module (PCM) to modify spark advance and
boost schedules in order to eliminate detonation.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The MAP sensor reacts to absolute pressure in the
intake manifold and provides an input voltage to the
powertrain control module (PCM). As engine load
changes, manifold pressure varies. The changes in
engine load cause the MAP output voltage to change.
The change in MAP sensor output voltage results in
a different input voltage to the PCM.
The input voltage level supplies the PCM with infor-
mation relating to ambient barometric pressure during
engine start-up (cranking) and engine load while its op-
erating. The PCM uses this input along with inputs
from other sensors to adjust air-fuel mixture.
On Turbo III engines, the MAP sensor is mounted
to the front right fender (Fig. 33) On 3.3L and 3.8L
engines, the MAP sensor (Fig. 34) is mounted to the
side of the intake manifold, below the positive crank-
case ventilation (PCV) valve. The sensor is connected
to the PCM electrically.
AUTO SHUTDOWN (ASD) RELAY AND FUEL PUMP
RELAY
The powertrain control module (PCM) operates the
auto shutdown (ASD) relay and fuel pump relay
through one ground path. The PCM operates the re-
lays by switching the ground path on and off. Both
relays turn on and off at the same time.
Fig. 32 Knock SensorÐTurbo III Engine
Fig. 30 Coolant Temperature SensorÐTurbo III En- gines
Fig. 31 Coolant Temperature SensorÐ3.3L and 3.8LEngines
8D - 32 IGNITION SYSTEMS Ä

FAILURE TO START TEST
This no-start test checks the camshaft position sen-
sor and crankshaft position sensor. The powertrain control module (PCM) supplies 8.0
volts to the camshaft position sensor and crankshaft
position sensor through one circuit. If the 8.0-volt
supply circuit shorts to ground, neither sensor will
produce a signal (output voltage to the PCM). When the ignition key is turned and left in the On
position , the PCM automatically energizes the auto shutdown (ASD) relay. However, the PCM de-energizes
the relay within one second because it has not received
a crankshaft position sensor signal indicating engine
rotation.
During cranking, the ASD relay will not energize
until the PCM receives a crankshaft signal. Secondly,
the ASD relay remains energized only if the PCM
senses a camshaft position sensor signal immediately
after detecting the crankshaft position sensor signal. (1) Check battery voltage. Voltage should approxi-
mately 12.66 volts or higher to perform failure to start
test. (2) Disconnect the harness connector from the coil
pack (Fig. 2). (3) Connect a test light to the B+ (battery voltage)
terminal of the coil electrical connector and ground.
The wire for the B+ terminal is dark green with a black
tracer. (4) Turn the ignition key to the ON position.The
test light should flash On and then Off. Do not turn
the Key to off position, leave it in the On position .
(a) If the test light flashes momentarily, the PCM
grounded the auto shutdown (ASD) relay. Proceed to
step 5. (b) If the test light did not flash, the ASD relay did
not energize. The cause is either the relay or one of
the relay circuits. Use the DRBII scan tool to test the
ASD relay and circuits. Refer to the appropriate
Powertrain Diagnostics Procedure Manual. Refer to
the wiring diagrams section for circuit information.
(5) Crank the engine. If the key was placed in the off
position after step 4, place the key in the On position
before cranking. Wait for the test light to flash once,
then crank the engine. (a) If the test light momentarily flashes during
cranking, the PCM is not receiving a camshaft posi-
tion sensor signal. Use the DRBII scan tool to test the
camshaft position sensor and sensor circuits. Refer to
the appropriate Powertrain Diagnostics Procedure
Manual. Refer to the wiring diagrams section for
circuit information. (b) If the test light did not flash during cranking,
unplug the camshaft position sensor connector. Turn
the ignition key to the off position. Turn the key to
the On position, wait for the test light to momen-
tarily flash once, then crank the engine. If the test
light momentarily flashes, the camshaft position
sensor is shorted and must be replaced. If the light
did not flash, the cause of the no-start is in either the
crankshaft position sensor/camshaft position sensor
8.0-volt supply circuit, or the crankshaft position
sensor 5-volt output or ground circuits. Use the
DRBII scan tool to test the crankshaft position sen-
sor and the sensor circuits.
Fig. 6 Ignition Coil Electrical Connection
Fig. 7 Ignition Coil Terminal Identification
Fig. 8 Checking Ignition Coil Secondary Resistance
Ä IGNITION SYSTEMS 8D - 37

(2) With engine running, move test probe along
entire length of all cables (approximately 0 to 1/8
inch gap). If punctures or cracks are present there
will be a noticeable spark jump from the faulty area
to the probe. Cracked, leaking or faulty cables should
be replaced. Use the following procedure when removing the
high tension cable from the spark plug. First, remove
the cable from the retaining bracket. Then grasp the
terminal as close as possible to the spark plug. Ro-
tate the cover (boot) slightly and pull straight back.
Do not use pliers and do not pull the cable at an
angle. Doing so will damage the insulation, cable
terminal or the spark plug insulator. Wipe spark
plug insulator clean before reinstalling cable
and cover. Resistance cables are identified by the words Elec-
tronic Suppression .
Use an ohmmeter to check cables for opens, loose
terminals or high resistance. (a) Remove cable from spark plug.
(b) Remove cable from the coil tower.
(c) Connect the ohmmeter between spark plug
end terminal and the coil end terminal. Resistance
should be within tolerance shown in the cable re-
sistance chart. If resistance is not within tolerance,
replace cable assembly. Test all spark plug cables
in same manner.
SPARK PLUG SERVICE
When replacing the spark plug cables, route the ca-
bles correctly and secure them in the appropriate re-
tainers. Incorrectly routed cables can cause the radio
to reproduce ignition noise. It can also cause cross ig-
nition of the spark plugs or short circuit the cables to
ground.
SPARK PLUG REMOVAL
Always remove cables by grasping at boot, rotating
the boot 1/2 turn, and pulling straight back in a
steady motion. (1) Prior to removing the spark plug spray com-
pressed air around the spark plug hole and the area
around the spark plug. (2) Remove the spark plug using a quality socket
with a rubber or foam insert. (3) Inspect the spark plug condition. Refer to
Spark Plug Condition in this section.
SPARK PLUG GAP ADJUSTMENT
Check the spark plug gap with a gap gauge. If the
gap is not correct, adjust it by bending the ground
electrode (Fig. 6).
SPARK PLUG INSTALLATION
(1) To avoid cross threading, start the spark plug
into the cylinder head by hand. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.)
torque. (3) Install spark plug cables over spark plugs.
IDLE RPM TEST
WARNING: BE SURE TO APPLY PARKING BRAKE
AND/OR BLOCK WHEELS BEFORE PERFORMING
ANY ENGINE RUNNING TESTS.
Engine idle set rpmshould be tested and recorded
as it is when the vehicle is first brought into shop
for testing. This will assist in diagnosing complaints
of engine stalling, creeping and hard shifting on ve-
hicles equipped with automatic transaxle. Refer to the
Throttle Body Minimum Airflow procedures in Group
14.
IGNITION TIMING PROCEDURE
Ignition timing cannot be changed or set on Turbo
III, 3.3L or 3.8L engines. For diagnostic information,
refer to the DRBII scan tool and the appropriate
Powertrain Diagnostics Procedures manual.
CABLE RESISTANCE CHART
Fig. 6 Setting Spark Plug GapÐTypical
Ä IGNITION SYSTEMS 8D - 41

CAMSHAFT POSITION SENSORÐ3.3L AND 3.8L
ENGINES
REMOVAL
(1) Disconnect camshaft position sensor electrical
connector from the wiring harness (Fig. 12). (2) Remove engine mount support bracket.
(3) Loosen camshaft position sensor retaining bolt
enough to allow slot in sensor to slide past the bolt. (4) Pull sensor up out of the chain case cover. Do not
pull on the sensor lead. There is an O-ring on the
sensor case. The O-ring may make removal difficult. A
light tap to top of sensor prior to removal may reduce
force needed for removal.
INSTALLATION
If installing the original sensor, clean off the
old spacer on the sensor face. A NEW SPACER
must be attached to the face before installation.
Inspect O-ring for damage, replace if necessary. If the
sensor is being replaced, confirm that the paper spacer is attached to the face and O-ring is posi-
tioned in groove of the new sensor (Fig. 13).
(1) Apply a couple drops of clean engine oil to the
O-ring prior to installation. Install sensor in the
chain case cover and push sensor down until contact
is made with the camshaft timing gear. While hold-
ing the sensor in this position, install and tighten
the retaining bolt 14 N Im (125 in. lbs.) torque.
(2) Connect camshaft position sensor electrical con-
nector to harness connector. Position connector away
from the accessory belt. (3) Install engine mount support bracket.
IGNITION COIL SERVICEÐTURBO III ENGINE
(1) Remove spark plug cables from coil (Fig. 14).
(2) Remove electrical connector from coil pack.
(3) Remove ignition coil fasteners.
(4) Reverse the above procedure for installation.
Tighten fasteners to 12 N Im (105 in. lbs.) torque.
IGNITION COILÐ3.3L AND 3.8L ENGINE
(1) Remove spark plug cables from coil (Fig. 15).
(2) Remove ignition coil electrical connector.
(3) Remove ignition coil mounting screws.
(4) Remove ignition coil.
Fig. 12 Camshaft Position Sensor LocationÐ3.3L and 3.8L Engine
Fig. 13 Camshaft Position SensorÐ3.3L and 3.8L Engines
Fig. 10 Camshaft Position Sensor LocationÐTurboIII Engines
Fig. 11 Camshaft Position SensorÐTurbo III Engine
Ä IGNITION SYSTEMS 8D - 43

IGNITION SWITCH
IGNITION SWITCH AND KEY CYLINDER SERVICE
The ignition switch is located on the steering col-
umn. The Key In Switch is located in the ignition
switch module. For diagnosis of the Key In Switch,
refer to Section 8M.
REMOVAL
If the vehicle has a floor mounted gear shifter,
place the selector in the Park position. (1) Disconnect negative cable from battery.
(2) If the vehicle has a tilt column, remove the tilt
lever by turning it counterclockwise. (3) Remove upper and lower covers from steering
column.
(4) Remove ignition switch mounting screws. Use
tamper proof torx bit Snap-on TTXR15A2, TTXR20A2
or equivalent to remove the screws (Fig. 1). (5) Gently pull switch away from the column. Release
connector locks on the 7 terminal wiring connector,
then remove the connector from the ignition switch.
(6) Release connector lock on the 4 terminal con-
nector, then remove the connector from the ignition
switch. (7) To remove the key cylinder from the ignition
switch: (a) Insert key in the ignition switch. Turn the
key to the LOCK position. Using a small screw-
driver, depress the key cylinder retaining pin until
it is flush with the key cylinder surface (Fig. 2). (b) Rotate the key clockwise to the OFF position.
The key cylinder will unseat from the ignition
switch (Fig. 3). When the key cylinder is unseated,
it will be approximately 1/8 inch away from the ig-
nition switch halo light ring. Do not attempt to
remove the key cylinder at this time. (c) With the key cylinder in the unseated posi-
tion, rotate the key counterclockwise to the lock po-
sition and remove the key. (d) Remove key cylinder from ignition switch
(Fig. 4).
INSTALLATION
If the vehicle has a floor mounted gear shifter,
place the selector in the Park position.
IGNITION SWITCH DESIGNATIONS
Fig. 1 Ignition Switch Screw Removal
Fig. 2 Key Cylinder Retaining Pin
Ä IGNITION SYSTEMS 8D - 45

(1) Connect electrical connectors to the ignition
switch. Make sure that the switch locking tabs are fully
seated in the wiring connectors. (2) Before attaching the ignition switch to a tilt
steering column, the transaxle shifter must be in the
Park position. Also the park lock dowel pin and the
column lock flag must be properly indexed before
installing the switch (Fig. 5). (a) Place the transaxle shifter in the PARK posi-
tion. (b) Place the ignition switch in the lock position.
The switch is in the lock position when the column
lock flag is parallel to the ignition switch terminals
(Fig. 5). (c) Position ignition switch park lock dowel pin so
it will engage the steering column park lock slider
linkage (Fig. 6). (d) Apply a light coating of grease to the column
lock flag and the park lock dowel pin.
(3) Place the ignition switch against the lock hous-
ing opening on the steering column. Ensure ignition
switch park lock dowel pin enters the slot in the park
lock slider linkage in the steering column. (4) Install ignition switch mounting screws. Tighten
screws to 2 N Im (17 in. lbs.) torque.
(5) Install steering column covers. Tighten screws to
2N Im (17 in. lbs.) torque.
(6) If the vehicle is equipped with a tilt steering
column, install the tilt lever. (7) To install the ignition key in the lock cylinder:(a) With the key cylinder and the ignition switch
in the Lock position, insert the key cylinder into the
ignition switch until it bottoms. (b) Insert ignition key into lock cylinder. While
gently pushing the key cylinder in toward the igni-
tion switch, rotate the ignition key until to the end of
travel. (c) Connect negative cable to battery.
(8) Check for proper operation of the halo light, shift
lock (if applicable), and column lock. Also check for
proper operation of the ignition switch accessory, lock,
off, run, and start positions.
Fig. 3 Unseated Key Cylinder
Fig. 4 Key Cylinder Removal
Fig. 5 Ignition Switch View From Column
Fig. 6 Ignition Switch Mounting Pad
8D - 46 IGNITION SYSTEMS Ä

shield washer fluid, door ajar for each door, and
trunk ajar. It also includes headlamp out, tail lamp
out, and brake lamp out warning lights (Fig. 3),
these lights are operated by a lamp outage module.
When there is no message center there is no door
ajar function.
TRAVELER
The traveler is a five function trip computer. It
uses vacuum fluorescent displays to display: trip
miles, instantaneous fuel economy, trip elapsed time,
trip average fuel economy and, estimate distance to
empty. It is located in the message center (Fig. 4).
WARNING LAMPS AND INDICATOR LIGHTS
The mechanical instrument cluster assemblies
have warning lamps and indicator lights for ten dif-
ferent systems. These include left and right turn sig-
nals, low fuel level, low oil pressure, high beam indicator, seat belt reminder, brake system, malfunc-
tion indicator (check engine) lamp, check gauges, an-
ti-lock system and air bag system indicator. The low oil pressure indicator replaces the Check
Gauges indicator in the cluster assembly without a
tachometer. In the cluster assembly with tachometer, Check
Gauges indictor illuminates in a warning situation.
This will notify driver to check for a problem in cool-
ant temperature, oil pressure or electrical systems.
CLUSTER AND GAUGE SERVICE AND TESTING
CAUTION: Disconnect battery cable. Before servic-
ing the instrument panel. Reconnect battery cable
when power is required for test purposes.
FUEL GAUGEÐFLEXIBLE FUEL
The flexible fuel vehicle uses a dampened fuel
gauge. Methanol fuel causes erratic gauge movement
if the proper gauge is not used. The unique fuel gauge may be identified by either
a green logo on the face of the gauge or by checking
the part number. Remove cluster from the instru-
ment panel and check the part number on top of the
cluster. Refer to Mechanical/Electronic Cluster Re-
moval for proper procedures. Refer to parts catalog
for proper part number.
Fig. 3 Message Center
Fig. 4 Traveler and Message Center
8E - 2 INSTRUMENT PANEL AND GAUGES Ä

SENDING UNIT TEST
When a problem occurs with a cluster gauge, be-
fore disassembling the cluster to check the gauge,
check for a defective sending unit or wiring. (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 oil, fuel or tempera-
ture gauge to read at or above maximum.
LOW OIL PRESSURE/CHECK GAUGES WARNING LAMP TEST
The low oil pressure/check gauges warning lamp
will illuminate when the ignition key is turned to
the ON position without starting the vehicle. In the cluster assembly without tachometer, the
low oil pressure lamp will illuminate if the engine oil
pressure drops below a safe oil pressure level. In the cluster assembly with tachometer, the Check
Gauges warning lamp illuminates when there is a
problem in oil pressure level, high engine tempera-
ture or 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
unit, which is located at the front of the engine (Figs.
5 and 6). If the wire at the connector checks good,
pull connector loose from the switch terminal and
with a jumper wire ground connector to the engine
(Fig. 7). With the ignition key turned to the ON po-
sition check the warning lamp. If lamp still fails to
light, inspect for a burned out lamp or disconnected
socket in the cluster.
COMBINATION OIL UNIT TEST
The combination oil unit has two functions:
(1) The normal closed circuit keeps the oil pressure
warning/check gauges lamp on until there is oil pres-
sure (Fig. 7). (2) The sending unit provides a resistance that
varies with oil pressure. (3) To test the normally closed oil lamp circuit, dis-
connect 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. (4) If there is oil pressure, the ohmmeter should
read an open circuit. (5) To test the sending unit, measure the resis-
tance between the sending unit terminal and the
metal housing. The ohmmeter should read open.
Start the engine. (6) The ohmmeter should read between 30 to 55
ohms, depending on engine speed, oil temperature,
and oil viscosity. (7) If the above results are not obtained, replace
the switch.
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 orFig. 5 Combination Oil Unit (2.5L)
Fig. 6 Combination Oil Unit (3.0L)
Fig. 7 Combination Oil Unit Test
Ä INSTRUMENT PANEL AND GAUGES 8E - 3

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. 8 and 9).
CAUTION: If wheel cylinder bleeder was opened
check master cylinder fluid level.
SEAT BELT WARNING SYSTEM
For testing of this system refer to Group 8M, Re-
straint Systems.
MALFUNCTION INDICATOR (CHECK ENGINE) SYSTEM
For testing this system refer to the Powertrain Di-
agnostic Test Procedures booklet.
AIR BAG WARNING SYSTEM
For testing this system refer to Group 8M, Re-
straint Systems.
Fig. 8 Brake Warning Lamp Switch
Fig. 9 Brake System Warning Lamp Diagnosis
8E - 4 INSTRUMENT PANEL AND GAUGES Ä

CONDITION: SPEEDOMETER AND ODOMETER ARE INOPERATIVE OR OPERATESINTERMITTENTLY
PROCEDURE
Check for defective vehicle speed sensor wiring.
CONDITION: OIL GAUGE, FUEL GAUGE, TEMPERATURE GAUGE, OR VOLTAGE GAUGEINOPERATIVE
PROCEDURE
Check for defective sending unit or wiring: (a) Sending units and wiring can be checked by
grounding the connector leads, at the sending unit,
in the vehicle. (b) With the ignition in the ON position, a
grounded input will cause the oil, fuel, or temper-
ature gauge to read maximum.
CONDITION: CLUSTER DISPLAY DOES NOT DIM WHEN HEADLAMP SWITCH ISACTIVATED AND RHEOSTAT ROTATED
PROCEDURE
(1) Check fuses in headlamp circuit.
(2) Check for loose connections or defective wiring
from headlamp switch to the cluster. (3) Check for defective headlamp switch.
(4) The electronic instrument cluster requires both
a marker feed and illumination feed to operate cor-
rectly.
SWITCH AND PANEL COMPONENT SERVICE
HEADLAMP/FOG LAMP SWITCH REPLACEMENT
(1) Remove cluster bezel (Fig. 40).
(2) Remove three screws securing headlamp switch
mounting plate to base panel (Fig. 41). (3) Pull headlamp/fog lamp switch mounting plate
rearward. Disconnect wiring connectors from head-
lamp switch and fog lamp switch pigtail (Fig. 42). (4) Remove knob and stem by depressing button on
bottom of the switch (Fig. 43). (5) Snap-out escutcheon.
(6) Remove fog lamp switch from escutcheon.
(7) Remove nut that attaches headlamp switch to
mounting plate (Fig. 44). (8) For installation reverse above procedures.
FOG LAMP SWITCH TEST
(1) Remove the fog lamp switch from mounting lo-
cation. (2) Disconnect the wiring harness from the switch
pigtail. (3) Using a Ohmmeter, test for continuity between
the terminals of the switch pigtail (Fig. 45). (4) If not OK, replace switch.
LOWER STEERING COLUMN COVERREPLACEMENT
(1) Disconnect park brake release rod from park
brake. (2) Remove fuse box access door and remove screw
from lower column cover (Fig. 46). (3) Remove screws from lower cover, four across
the top and two on bottom. (4) Remove lower steering column cover.
(5) For installation reverse above procedures.
LEFT LOWER INSTRUMENT PANEL SILENCER REPLACEMENT
(1) Remove screws from front of silencer (Fig. 47).
(2) Remove push nut.
(3) Remove silencer.
(4) For installation reverse above procedures.
RIGHT LOWER INSTRUMENT PANEL SILENCER REPLACEMENT
(1) On floor shift vehicles, remove console assem-
bly and center brace bracket. (2) On column shift vehicles, remove center brace
bracket. (3) Remove screws from front of silencer (Fig. 47).
(4) Remove three push nuts from rear of silencer.
(5) Remove lower right silencer.
(6) For installation reverse above procedures.
GLOVE BOX ASSEMBLY REPLACEMENT
(1) Disconnect battery negative cable and isolate
or remove fuse #2 prior to removing switch or wires
may short to ground. (2) Open glove box door and disconnect check
strap. (3) Remove glove box light and switch by squeez-
ing retaining tabs from behind switch mount and
slide rearward. Disconnect wiring connectors. (4) Remove 11 screws from glove box assembly
(Fig. 48). (5) Remove glove box assembly.
Fig. 36 Electronic Cluster
Ä INSTRUMENT PANEL AND GAUGES 8E - 15