1993 CHEVROLET DYNASTY sensor

The Engine Compartment Node is located behind
the grille. For complete diagnostic procedures for the Engine
Compartment Node, refer to the Body Diagnostic
Test Procedure Manual.
ENGINE COMPARTMENT NODE COMPASS
CALIBRATION
Automatic or Manual Calibration, refer to AY
Body Compass Calibration.
THERMOMETER AND COMPASS
OPERATION
The ignition switch must be in the ON or ACCES-
SORY position before the temperature and compass
reading can be displayed. The Comp/Temp switch
turns the compass display on and off. The US/Metric
switch changes the temperature reading from Fahr-
enheit to Celsius (Fig. 4). When the vehicle is standing still, engine compart-
ment temperatures may be radiated to the tempera-
ture sensor. Therefore the most accurate ambient
temperature readings are displayed when the vehicle
is moving in a forward motion. When the ignition switch is in the ON position the
temperature display is updated every 5 minutes.
When the ignition switch is turned off the last dis-
played temperature reading stays in memory. When the ignition switch is turned on again the thermom-
eter will display the memory temperature for 1
minute; then update the display to the actual tem-
perature within 5 minutes.
COMPASS CALIBRATION
Do not attempt to set the compass near large metal
objects, such as, other vehicles, large buildings, or
bridges. The compass unit automatically calibrates itself as
the vehicle is driven; therefore, no calibration should
be required. When the compass is first powered up,
the CAL light on the display should be on. The CAL
light will go off and the compass will be accurate af-
ter the vehicle completes 1 to 3 complete circles. If the vehicle's compass headings are inaccurate,
the compass also can be manually calibrated using
the following procedures: (1) Depress and hold down both the Comp/Temp
button and the U.S./Metric button. (2) The display will go off and after 5 seconds the
VAR light will come on. Continue to hold both but-
tons down. (3) In approximately 10 seconds, the CAL light
will come on. Release both buttons and the display
will show the heading and outside temperature.
Fig. 4 Overhead Console
8C - 16 OVERHEAD CONSOLE Ä

OVERHEAD CONSOLE REPLACEMENT
(1) Unscrew the mounting screw in sun glass bin
compartment (Fig. 8).
(2) Slide console forward toward windshield until
the console unhooks from roof bracket. (3) Disconnect wire harness from console.
(4) For installation reverse above procedures.
COMPASS MODULE REPLACEMENT
(1) Remove overhead console.
(2) Using a small screwdriver, release the 2 snaps
at rear of compass module (Fig. 9).
(3) After releasing the 2 snaps, slide compass mod-
ule rearward until free of mounting bar. (4) For installation reverse above procedures.
ELECTRONIC VEHICLE INFORMATION CENTER
(EVIC) REMOVAL
(1) Use a straight edge tool to pry out one end of
the EVIC center and continue to disengage six clips
along the length of the message center. (2) Remove the EVIC center and disconnect the
wiring. (3) For installation reverse the above procedures.
AMBIENT TEMPERATURE SENSOR REMOVAL
(1) Raise and support vehicle on safety stands.
(2) From behind front bumper fascia, remove screw
attaching sensor to radiator closure panel (Fig. 10).
(3) For installation, reverse above procedures.
ENGINE NODE SENSOR REMOVAL
(1) Raise and support vehicle on safety stands.
(2) From behind front bumper fascia, remove
screws attaching engine node to bumper fascia (Fig.
11). (3) For installation, reverse above procedures.
Fig. 8 Overhead Console Mounting
Fig. 9 Compass Module Removal
Fig. 10 Ambient Temperature Sensor
Fig. 11 Engine Node
8C - 20 OVERHEAD CONSOLE Ä

AP BODY INDEX
page page
Ambient Temperature Sensor Removal ........ 25
Compass Calibration ...................... 21
Compass Diagnostics ..................... 23
Compass Module Replacement .............. 25
Demagnetizing Procedure .................. 22 Map Reading Lamps Operation
.............. 21
Overhead Console Replacement ............. 25
Thermometer and Compass ................ 21
Variance Procedure ....................... 22
MAP READING LAMPS OPERATION
The map lamps are actuated by pressing on the
lens (Fig. 1).
LAMP REPLACEMENT
(1) Remove lens by inserting a screw driver or
knife blade into slot located along-side of lens. Once
screwdriver is inserted pry lens to the side and swing
down as it unhooks from housing edge. (2) Remove lamp by pulling straight down.
(3) Install new lamp by pushing firmly into recep-
tacle. (4) Snap lens into position taking care to orient
the tabs on the lens with the slots in the housing.
MAP LAMP TEST
(1) Press each lamp switch. Right hand switch
should light passenger lamp and left hand switch
should light drivers lamp. (2) If lamp does not illuminate check for a burned
out lamp, voltage, defective switch or faulty wiring.
THERMOMETER AND COMPASS
The ignition switch must be in the ON or ACCES-
SORY position before the temperature and compass
reading can be displayed. The Comp/Temp switch
turns the compass display on and off. The US/Metric
switch changes the temperature reading from Fahr-
enheit to Celsius (Fig. 2). When the vehicle is standing still, engine compart-
ment temperatures may be radiated to the tempera-
ture sensor. Therefore the most accurate ambient
temperature readings are displayed when the vehicle
is moving in a forward motion. When the ignition switch is in the ON position the
temperature display is updated every 5 minutes.
When the ignition switch is turned off the last dis-
played temperature reading stays in memory. When
the ignition switch is turned on again the thermom-
eter will display the memory temperature for 1
minute; then update the display to the actual tem-
perature within 5 minutes.
COMPASS CALIBRATION
Do not attempt to set the compass near large metal
objects, such as, other vehicles, large buildings, or
bridges. The compass unit automatically calibrates itself as
the vehicle is driven; therefore, no calibration should
be required. When the compass is first powered up,
the CAL light on the display should be on. The CAL
light will go off and the compass will be accurate af-
ter the vehicle completes one to three complete cir-
cles. If the vehicle's compass headings are inaccurate,
the compass also can be manually calibrated using
the following procedures: (1) Depress and hold down both the Comp/Temp
button and the U.S./Metric button. (2) The display will go off and after 5 seconds the
VAR light will come on. Continue to hold both but-
tons down. (3) In approximately 10 seconds, the CAL light
will come on. Release both buttons and the display
will show the heading and outside temperature. (4) Drive the vehicle 1 to 3 complete circles, with-
out turning ignition OFF. The CAL light will then
go off, showing the compass is calibrated.
Fig. 1 Overhead Console Lamp Replacement
Ä OVERHEAD CONSOLE 8C - 21

Test 3 (d3) performs a walking segment test which,
sequentially puts different directions and numbers on
the display. If any segment fails, replace the compass
module.
OVERHEAD CONSOLE REPLACEMENT
(1) Unscrew the mounting screw in sun glass bin
compartment (Fig. 6).
(2) Slide console forward toward windshield until
the console unhooks from roof bracket. (3) Disconnect wire harness from console.
(4) For installation reverse above procedures.
COMPASS MODULE REPLACEMENT
(1) Remove overhead console (Fig 6).
(2) Using a small screwdriver, release the 2 snaps
at rear of compass module (Fig. 7). (3) After releasing the 2 snaps, slide compass mod-
ule rearward until free of mounting bar. (4) For installation reverse above procedures.
AMBIENT TEMPERATURE SENSOR REMOVAL
(1) Raise and support vehicle on safety stands.
(2) Behind front bumper fascia, remove screw at-
taching sensor to radiator closure panel (Fig. 8). (3) For installation, reverse above procedures.
Fig. 6 Overhead Console Mounting
Fig. 7 Compass Module Removal
Fig. 8 Ambient Temperature Sensor
Ä
OVERHEAD CONSOLE 8C - 25

IGNITION SYSTEMS
CONTENTS
page page
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐDIAGNOSTIC PROCEDURES
..... 11
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNI- TION SYSTEMSÐSERVICE PROCEDURES . 14
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNI- TION SYSTEMSÐSYSTEM OPERATION .... 1
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMÐDIAGNOSTIC PROCEDURES
.... 35
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMÐSYSTEM OPERATION ......... 24
2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMSÐSERVICE PROCEDURES ...... 39
IGNITION SWITCH ...................... 45
SPECIFICATIONS ....................... 47
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicles by letter designation. A chart ex-
plaining the designations appears in the Introduction
Section of this manual.
2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐSYSTEM OPERATION
INDEX
page page
Auto Shutdown (ASD) Relay and Fuel Pump Relay . 8
Coolant Temperature Sensor ................. 7
Distributor Cap ........................... 1
Distributor Pick-UpÐ3.0L Engine .............. 7
Distributor Pick-UpÐPCM Input ............... 6
General Information ........................ 1 Ignition Coil
.............................. 9
Manifold Absolute Pressure (MAP) Sensor ...... 8
Powertrain Control Module (PCM) ............. 6
Rotor .................................. 2
Spark Plug Cables ........................ 2
Spark Plugs ............................. 3
GENERAL INFORMATION
This section describes the ignition systems of the
2.2L TBI, 2.5L TBI, 2.5L MPI (flexible fuel AA-body)
and 3.0L engines. The Fuel Injection sections of Group 14 explain On
Board Diagnostics. Group 0, Lubrication and Maintenance, contains
general maintenance information for ignition related
items. The Owner's Manual also contains mainte-
nance information.
DISTRIBUTOR CAP
Remove the distributor cap and inspect the inside
for flash over, cracking of carbon button, lack of
spring tension on carbon button, cracking of cap, and
burned, worn terminals (Fig. 1). Also check for bro-
ken distributor cap towers. If any of these conditions
are present the distributor cap and/or cables should
be replaced. When replacing the distributor cap, transfer cables
from the original cap to the new cap one at a time.
Ensure each cable is installed into the corresponding tower of the new cap. Fully seat the wires into the
towers. If necessary, refer to the appropriate engine
firing order diagram (Fig. 2 or Fig. 3).
Fig. 1 Distributor Cap Inspection
Ä
IGNITION SYSTEMS 8D - 1

pick-up (a Hall Effect device and magnet) through
which the shutter blades rotate. As the shutter
blades pass through the pick-up, they interrupt the
magnetic field. The Hall effect device in the pick-up
senses the change in the magnetic field and switches
on and off (which creates pulses), generating the in-
put signal to the PCM. The PCM calculates engine
speed through the number of pulses generated. On 2.5L MPI (flexible fuel AA-Body) engines, one
of the shutter blades has a window cut into it. The
PCM determines injector synchronization from the
window. Also, the PCM uses the input for detonation
control.
DISTRIBUTOR PICK-UPÐ3.0L ENGINE
The distributor pick-up provides two inputs to the
powertrain control module (PCM). From one input
the PCM determines RPM (engine speed). From the
other input it derives crankshaft position. The PCM
regulates injector synchronization and adjusts igni-
tion timing and engine speed based on these inputs. The distributor pick-up contains two signal gener-
ators. The pick-up unit consists of 2 light emitting
diodes (LED), 2 photo diodes, and a separate timing
disk. The timing disk contains two sets of slots. Each
set of slots rotates between a light emitting diode
and a photo diode (Fig. 17). The inner set contains 6
large slots, one for each cylinder. The outer set con-
tains several smaller slots. The outer set of slots on the rotating disk repre-
sents 2 degrees of crankshaft rotation. Up to 1200
engine RPM, the PCM uses the input from the outer
set of slots to increase ignition timing accuracy. The outer set of slots contains a 10 degree flat spot.
This area is not slotted (Fig. 17). The flat spot tells
the PCM that the next piston at TDC will be number
6. Each piston's position is referenced by one of the
six inner slots (Fig. 18). As each slot on the timing disk passes between the
diodes, they interrupt the beam from the light emit-
ting diode. This creates an alternating voltage in
each photo diode which is converted into on-off
pulses. The pulses are the input to the PCM. During cranking, the PCM cannot determine which
cylinder will be at TDC until the 10 degree flat spot
on the outer set of slots rotates through the optical
unit. Once the flat spot is detected, the PCM knows
piston number 6 will be the next piston at TDC. Since the disk rotates at half crankshaft speed, it
may take up to 2 engine revolutions during cranking
before the PCM determines the position of piston
number 6. For this reason the PCM energizes all six
injectors at the same time until it senses the position
of piston number 6.
COOLANT TEMPERATURE SENSOR
On 2.2L TBI, 2.5L TBI and 2.5L MPI engines, the
coolant temperature sensor is installed behind the
thermostat housing and ignition coil in the hot box
(Fig. 19). On 3.0L engines the sensor is located next
Fig. 16 DistributorÐ2.5L MPI (Flexible Fuel AA-Body)Fig. 17 Distributor Pick-upÐ3.0L Engine
Fig. 18 Inner and Outer Slots of Rotating DiskÐ3.0L Engine
Ä IGNITION SYSTEMS 8D - 7

to the thermostat housing (Fig. 20). The sensor pro-
vides an input voltage to the powertrain control mod-
ule (PCM). The sensor is a variable resistance
(thermistor) with a range of -40ÉF to 265ÉF. As cool-
ant temperature varies, the sensors resistance
changes, resulting in a different input voltage to the
PCM. The PCM contains different spark advance sched-
ules for cold and warm engine operation. The sched-
ules reduce engine emissions and improve
driveability. Because spark advance changes at dif-
ferent engine operating temperatures during warm-
up, all spark advance testing should be done with the
engine fully warmed. The PCM demands slightly richer air-fuel mixtures
and higher idle speeds until the engine reaches nor-
mal operating temperature. The coolant sensor input is also used for radiator
fan control.
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 causes the MAP sensors 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 in-
formation relating to ambient barometric pressure
during engine start-up (cranking) and engine load
while its operating. The PCM uses this input along
with inputs from other sensors to adjust air-fuel mix-
ture. On 2.2L TBI, 2.5L TBI and 2.5L MPI (flexible fuel
AA-body) engines, the MAP sensor is mounted to the
dash panel (Fig. 21 or Fig. 22). On 3.0L engines, the
sensor is mounted to a bracket across from the dis-
tributor (Fig. 23). The sensor is connected to the
throttle body or intake manifold with a vacuum hose
and 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. The ASD relay connects battery voltage to the fuel
injector and ignition coil. The fuel pump relay con-
nects battery voltage to the fuel pump and oxygen
sensor heating element. The PCM turns the ground path off when the igni-
tion switch is in the Off position. Both relays are off.
When the ignition switch is in the On or Crank po-
sition, the PCM monitors the distributor pick-up sig-
Fig. 19 Coolant Temperature SensorÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 20 Coolant Temperature SensorÐ3.0L Engines
Fig. 21 MAP SensorÐ2.2L and 2.5L TBI Engines
8D - 8 IGNITION SYSTEMS Ä

nal. From the pick-up signal, the PCM determines
engine speed and ignition timing (coil dwell). If the
PCM does not receive a distributor signal when the
ignition switch is in the Run position, it will de-en-
ergize both relays. When the relays are de-energized,
battery voltage is not supplied to the fuel injector, ig-
nition coil, fuel pump and oxygen sensor heating el-
ement. On AC, AG, AJ and AY models, the ASD relay and
fuel pump relay are located in the power distribution
center (Fig. 24, 25, 26, or 27). On AA and AP models, the ASD relay and fuel
pump relay are mounted on the drivers side fender
well, next to the strut tower (Fig. 28).
IGNITION COIL
The 2.2L TBI, 2.5L TBI, 2.5L MPI and 3.0L en-
gines use an epoxy type coil. The coils are not oil
filled. The windings are embedded in a heat and vi-
bration resistant epoxy compound. The powertrain control module (PCM) operates the
ignition coil through the auto shutdown (ASD) relay. When the relay is energized by the PCM, battery
voltage is connected to the ignition coil positive ter-
minal. The PCM will de-energize the ASD relay if it
does not receive an input from the distributor pick-
Fig. 22 MAP SensorÐ2.5L MPI (Flexible Fuel AA-Body) Engines
Fig. 23 MAP SensorÐ3.0L Engine
Fig. 24 Power Distribution Center (PDC) (AC Body)
Fig. 25 Relay Identification (AC Body)
Fig. 26 Power Distribution Center (PDC) (AG and AJ Body)
Ä IGNITION SYSTEMS 8D - 9