1993 CHEVROLET DYNASTY wheel

IGNITION OFF DRAW (IOD)
GENERAL INFORMATION
A normal electrical system will draw from 5 to 30
milliamperes from the battery. This is with the ignition
in the OFF position, and all non-ignition controlled cir-
cuits in proper working order. The amount of IOD will
depend on body model and electrical components. A ve-
hicle that has not been operated for an extended period
of approximately 20 days may discharge the battery to
an inadequate level. In this case, the Main Fusible Link
Connector should be disconnected. The Main Fusible
Link connector is located rearward of the battery on the
engine wiring harness (Fig. 19).
If the IOD is over 30 milliamperes, the defect must
be found and corrected before condemning the bat-
tery. Usually, the battery can be charged and re-
turned to service (Fig. 16).
IGNITION OFF DRAW (IOD) TESTS
VEHICLES WITHOUT ELECTRONIC AUTOMATIC TRANSMISSION/LOAD LEVELINGSUSPENSION OR ALARM SYSTEMS
Testing for HIGHER AMPERAGE IOD must be
performed first to prevent damage to most milliamp
meters. A standard 12 volt test light and a milliamp meter
that is equipped with two leads will be used for the
following tests. The milliamp meter should be able to
handle up to two amps.
(1) Verify that all electrical accessories are OFF.
Turn off all lights, close trunk lid, close glove box door,
turn off sun visor vanity lights, close all doors and re- move ignition key. Allow the Illuminated Entry System
if equipped to time out in approximately 30 seconds.
(2) Verify the engine compartment lamp bulb is
working by opening/closing hood. Remove the lamp. (3) Disconnect negative battery cable (Fig. 15).
(4) Connect a typical 12 volt test light between the
negative cable clamp and the negative battery post (Fig.
19). The test light may be brightly lit for up to three
minutes or may not be lit at all. This depending on the
body model or electronic components on the vehicle. (a) The term brightly used throughout the follow-
ing tests. This implies the brightness of the test light
will be the same as if it were connected across the
battery posts. This would be with a fully charged bat-
tery.
(b) The test light or the milliamp meter MUST
be positively connected to the battery post and the
battery cable during all IOD testing. (c) Do not allow the test light or the milliamp
meter to become disconnected during any of the
IOD tests. If this happens, the electronic timer
functions will be started and all IOD tests must be
repeated from the beginning. Clamp the test light
at both ends to prevent accidental disconnection.
(d) After three minutes time has elapsed, the test
light should turn OFF or be dimly lit depending on
the electronic components on the vehicle. If the test
light remains BRIGHTLY lit, do not disconnect test
light. Disconnect each fuse or circuit breaker until
test light is either OFF or DIMLY lit. Refer to the
Front Wheel Drive Car Wiring Diagrams Service
Manual. This will eliminate higher amperage IOD. It
is now safe to install the milliamp meter without
damage to the meter to check for low amperage IOD.
(e) Possible sources of high IOD are usually ve-
hicle lamps trunk lamp, glove compartment, lug-
gage compartment, etc.. (f) If test light is still brightly lit after discon-
necting each fuse and circuit breaker, disconnect
the wiring harness from the generator. Refer to
Generator Testing. Do not disconnect test light.
CAUTION: This last test has higher amperage IOD and
must be performed before going on with low amper-
age IOD tests. The higher amperage IOD must be elim-
inated before hooking up milliamp meter to check for
low amperage IOD. If higher amperage IOD has not
been eliminated, milliamp meter may be damaged.
Most milliamp meters will not handle over one or two
amps. Do not hook up meter if test light is glowing
brightly. Refer to maximum amperage specifications
and instructions supplied with milliamp meter.
After higher amperage IOD has been corrected, low
amperage IOD may be checked. The MAXIMUM IOD=
30 MILLIAMPERES.
Fig. 19 IOD Test
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 9

(5) With test light still connected, connect milli-
amp meter between battery negative post and nega-
tive battery cable (Fig. 20). Do not open any doors or
turn on any electrical accessories with the test light
disconnected and the milliamp meter connected.
Meter may be damaged.
(6) Disconnect test light. Milliamp meter reading
should be less than 30 milliamperes. If low amperage
IOD is not within specifications, disconnect: (a) The 60 way connector at the Powertrain Con-
trol Module located outboard of the battery. Refer
to Group 8D, Ignition for more information. (b) The 25 way connectors on the Body Control-
ler if equipped. (c) The circuits to the clock and radio.
(d) The wiring harness from the generator. Refer
to Generator Testing.
Check each component until excessive IOD is found.
Each time the test light or milliamp meter is dis-
connected and connected, all electronic timer func-
tions will be activated. Tests must be repeated from
the beginning. Test light or meter MUST remain connected for all
tests.
VEHICLES EQUIPPED WITH ELECTRONIC AUTOMATIC TRANSMISSION, LOADLEVELING SUSPENSION, OR ALARM SYSTEM
This vehicles will have temporary high IOD of 15
amps or more for up to 65 minutes. This higher IOD can often mask another problem and should be con-
sidered when performing IOD testing. Testing for higher IOD will be the same as in the
previous IOD tests. However, certain additional pro-
cedures should be followed.
² WITH ALARM SYSTEM: After disconnecting bat-
tery and hooking up test light, cycle the key lock on
the driver's door to disarm the alarm. The parking
lamps should stop flashing. Also locate the Power Distribution Center. This
Center is located in front of the left front strut tower
(Fig. 21). Remove the cover from the Center and re-
move the 50 amp fuse.
² WITH ELECTRONIC AUTOMATIC TRANSMIS-
SION: If equipped with this option, and high or low
IOD is suspected, allow an additional 25 minutes
minimum of electronic shut off time. To defeat the timer, disconnect the 60-way connec-
tor on the Transmission Controller. This controller is
located on the right inner fender.
² WITH AUTOMATIC LOAD LEVELING SYSTEM:
If equipped with this option, and high or low IOD is
suspected, allow an additional 65 minutes minimum
of electronic shut off time. To defeat the timer, open the trunk lid, locate the
Automatic Load Leveling computer, located inside
right rear wheel house, and disconnect the 11-way
connector. Close the trunk lid. If equipped with an electrical trunk closing feature,
temporarily install a heavy gauge jumper wire be-
tween the disconnected negative cable and the nega-
tive battery post. When this jumper is installed the
trunk lid should automatically close. Do not discon-
nect the test light as all electronic timing features
will be activated and all IOD tests must be repeated
from the beginning. Remove the temporarily installed jumper wire.
Fig. 20 Low Amperage IOD Test
Fig. 21 Power Distribution Center
8A - 10 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä

relay to starter solenoid for loose or corroded connec-
tions. Particularly at starter terminals.
² Repeat test. If engine still fails to crank properly,
trouble is within starter or starter mounted solenoid,
and it must be removed for repairs. Refer to Group
8B, Battery/Starter/Generator Service, Starter re-
placement.
STARTER RELAY TEST
WARNING: CHECK TO ENSURE THAT THE TRANS-
MISSION IS IN PARK OR NEUTRAL WITH THE
PARKING BRAKE APPLIED
(1) Verify battery condition. Battery must be in
good condition with a full charge before performing
any starter tests. Refer to Battery Tests. (2) Perform the preceding starter solenoid tests
BEFORE performing starter relay tests. Refer to
Starter Solenoid Test. (3) Locate and remove the starter relay. For
starter relay locations, refer to Starter Solenoid Test
(Fig. 13 or 14). (4) After the starter relay has been located and re-
moved, refer to Starter Relay Tests (Fig. 15).
NEUTRAL STARTING AND BACK-UP SWITCH
AUTOMATIC TRANSMISSION ONLY
For electrical diagnostics, when checking starter
circuits, refer to Starter Relay Tests (Fig. 15). For replacement of switch, refer to Group 21, Tran-
saxle, Neutral Starting and Switch Replacement.
STARTER INTERLOCK SWITCHÐCLUTCH PEDAL MOUNTED
MANUAL TRANSMISSION ONLY
For electrical diagnostics, refer to the Starter Relay
Tests. For replacement and/or adjustment of the switch,
refer to Group 6, Manual Transaxle Clutch, Manual
Transaxle Starter Interlock Switch.
IGNITION SWITCH TEST
After testing the starter solenoid and relay, test ig-
nition switch and wiring. Refer to Group 8D, Ignition
Systems, or the Front Wheel Drive Car Wiring Dia-
grams Service Manual. Check all wiring for opens or
shorts, and all connectors for being loose or corroded.
BENCH TESTING STARTER SOLENOID
(1) Disconnect field coil wire from field coil termi-
nal (Fig. 16 or 17). (2) Check for continuity between solenoid terminal
and field coil terminal with a continuity tester. Con-
tinuity should be detected (Fig. 18 or 19). (3) Check for continuity between solenoid terminal
and solenoid housing (Fig. 20 or 21). Continuity
should be detected. If continuity is detected, solenoid
is good. (4) If continuity is not detected in either test, sole-
noid has an open circuit and is defective. If equipped
with:
² BOSCH STARTER: Replace the solenoid.
² NIPPONDENSO STARTER: Replace the starter
assembly.
8A - 16 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä

NIPPONDENSO STARTER GEAR AND CLUTCH
REMOVAL AND INSTALLATION (1) Remove the two gear housing attaching screws
and separate the gear housing from the solenoid
housing (Fig. 10). The pinion gear, pinion gear bear-
ing, and drive gear will be loose between the solenoid
housing and gear housing (Fig. 11). When reinstall-
ing pinion gear and bearing, wipe with a clean rag
and coat with lightweight high temperature wheel
bearing grease. Place the lubricated bearing and
gear over the bearing shaft in the gear housing (Fig.
12). (2) Remove the starter gear and clutch assembly
from the solenoid housing (Fig. 13). (3) For assemble, reverse above procedures.
BOSCH STARTER SOLENOID REPLACEMENT
(1) Remove field terminal nut (Fig. 14).
(2) Remove field terminal (Fig. 15).
(3) Remove field washer (Fig. 16). (4) Remove three solenoid mounting screws (Fig.
17). (5) Remove the solenoid from the starter assembly.
(6) For installation, reverse above procedures.
Fig. 8 Remove/Install StarterÐBoschÐTypical
Fig. 9 Remove/Install
StarterÐNippondensoÐTypical
Fig. 10 Remove or Install Gear Housing
Fig. 11 Remove or Install Drive and Pinion Gears
Fig. 12 Lubricate and Install Pinion Gear Bearing
8B - 6 BATTERY/STARTER/GENERATOR SERVICE Ä

2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐDIAGNOSTIC PROCEDURES
INDEX
page page
Coolant Temperature Sensor Test ............ 13
Failure to Start TestÐ2.5L TBI and 3.0L Engines . 12
General Information ....................... 11
Ignition Coil ............................. 11 Manifold Absolute Pressure (MAP) Sensor Test . 13
Poor Performance Test .................... 13
Spark Plugs ............................ 11
Testing for Spark at Coil ................... 11
GENERAL INFORMATION
For additional information, refer to On Board Di-
agnostics in the Fuel Injection General Diagnosis
sections of Group 14. Also, refer to the DRBII scan
tool and appropriate Powertrain Diagnostic Proce-
dures Manual.
SPARK PLUGS
Faulty or fouled spark plugs may perform well at
idle speed, but frequently fail at higher engine
speeds. Faulty plugs can be identified in a number of
ways: poor fuel economy, power loss, decrease in en-
gine speed, hard starting and, in general, poor en-
gine performance. Spark plugs also malfunction because of carbon
fouling, excessive electrode air gap, or a broken insu-
lator. Refer to the General Information Section of
this group for spark plug diagnosis.
IGNITION COIL
The ignition coil is designed to operate without an
external ballast resistor. Inspect the coil for arcing. Test the coil according
to coil tester manufacturer's instructions. Test coil
primary and secondary resistance. Replace any coil
that does not meet specifications. Refer to the Coil
Resistance chart. If the ignition coil is replaced due to a burned
tower, carbon tracking, arcing at the tower, or dam-
age to the terminal or boot on the coil end of the sec-
ondary cable, the cable must be replaced. Arcing at the tower will carbonize the nipple which, if it is con-
nected to a new coil, will cause the coil to fail. If a secondary cable shows any signs of damage,
the cable should be replaced with a new cable and
new terminal. Carbon tracking on the old cable can
cause arcing and the failure of a new coil.
TESTING FOR SPARK AT COIL
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK THE WHEELS BEFORE PERFORMING ANY
TEST WITH THE ENGINE RUNNING.
CAUTION: Spark plug cables may be damaged if
this test is performed with more than 1/4 inch clear-
ance between the cable and engine ground.
Remove the coil secondary cable from the distribu-
tor cap. Hold the end of cable about 6 mm (1/4-inch)
away from a good engine ground (Fig. 1). Crank the
engine and inspect for spark at the coil secondary ca-
ble. There must be a constant spark at the coil second-
ary cable. If the spark is constant, have a helper con-
tinue to crank engine and, while slowly moving coil
secondary cable away from ground, look for arcing at
the coil tower. If arcing occurs at the tower, replace
the coil. If spark is not constant or there is no spark,
proceed to the failure to start test. If a constant spark is present and no arcing occurs
at the coil tower, the ignition system is producing
the necessary high secondary voltage. However,
COIL RESISTANCE
Ä IGNITION SYSTEMS 8D - 11

make sure that the spark plugs are firing. Inspect the
distributor rotor, cap, spark plug cables, and spark
plugs. If they are in proper working order, the ignition
system is not the reason why the engine will not start.
Inspect the fuel system and engine for proper opera-
tion.
FAILURE TO START TESTÐ2.5L TBI AND 3.0L
ENGINES
Before proceeding with this test make sure
Testing For Spark At Coil has been performed.
Failure to do this may lead to unnecessary diag-
nostic time and wrong test results.
WARNING: BE SURE TO APPLY PARKING BRAKE
AND/OR BLOCK WHEELS BEFORE PERFORMING
ANY TEST WITH THE ENGINE RUNNING.
(1) Battery voltage must be at least 12.4 volts to
perform test. (2) Crank the engine for 5 seconds while monitoring
the voltage at the coil positive (+) terminal (Fig. 2 or
Fig. 3). If the voltage remains near zero during the
entire period of cranking, refer to Group 14 for On-
Board Diagnostic checks. Also, refer to the DRBII scan
tool and the appropriate Powertrain Diagnostic Proce-
dures manual. These checks will help diagnose prob-
lems with the PCM and auto shutdown relay. (3) If voltage is at near-battery voltage and drops to
zero after 1-2 seconds of cranking, refer to On-Board
Diagnostic in Group 14. Also, refer to the DRBII scan
tool and the appropriate Powertrain Diagnostic Proce-
dures manual. These tests will help check the distribu-
tor reference pickup circuit to the PCM. (4) If voltage remains at near battery voltage during
the entire 5 seconds, with the key off,remove the
PCM 60-way connector. Check the 60-way connector
for any terminals that are pushed out or loose. (5) Remove the connector to coil (+) and connect a
jumper wire between battery (+) and coil (+). (6) Using the special jumper (Fig. 4), momentarily ground terminal #19 of the 60-way connector (Fig.
5). A spark should be generated when the ground is
removed.
(7) If spark is generated, replace the PCM.
(8) If no spark is seen, use the special jumper to
ground the coil (-) terminal directly. (9) If spark is produced, inspect wiring harness for
an open condition.
Fig. 2 Coil TerminalsÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 3 Coil TerminalsÐ3.0L Engine
Fig. 4 Special Jumper to Ground Coil Negative
Fig. 1 Checking for Spark
8D - 12 IGNITION SYSTEMS Ä

(10) If no spark is produced, replace the ignition coil.
POOR PERFORMANCE TEST
To prevent unnecessary diagnostic time and
possible incorrect results, the Testing For Spark
At Coil procedure should be performed before
this test.
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
THE WHEELS BEFORE PERFORMING ANY ENGINE
RUNNING TESTS.
Check and adjust basic timing (refer to the specifica-
tion section of this group and see service procedures).
COOLANT TEMPERATURE SENSOR TEST
(1) With key off, disconnect wire connector from
coolant temperature sensor (Fig. 6). (2) Connect one lead of ohmmeter to one terminal of
coolant temperature sensor. (3) Connect the other lead of ohmmeter to remaining
terminal of coolant temperature sensor. The ohmmeter
should read as follows;
² Engine/Sensor at normal operating temperature
around 200ÉF should read approximately 700 to 1,000
ohms.
² Engine/Sensor at room temperature around 70ÉF,
ohmmeter should read approximately 7,000 to 13,000
ohms. Refer to On Board Diagnostics in the General
Diagnosis section of Group 14. Also, refer to the
DRBII scan tool and the appropriate Powertrain
Diagnostic Procedures manual for additional
test procedures.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST
Refer to the DRB II scan tool and appropriate Pow-
ertrain Diagnostic Procedures manual for further test
procedures.
Fig. 5 60-Way Electrical Connector, Powertrain con- trol module
Fig. 6 Coolant Temperature Sensor Test
Ä IGNITION SYSTEMS 8D - 13

(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) Start the spark plug into the cylinder head by
hand to avoid cross threading. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.)
torque. (3) Install spark plug cables over spark plugs.
IDLE RPM TESTÐ2.5L AND 3.0L ENGINES
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING IDLE CHECK OR
ADJUSTMENT, OR ANY TESTS WITH A RUNNING
ENGINE.
Engine idle set rpmshould be recorded when the
vehicle is first brought into shop for testing. This
will assist in diagnosing complaints of engine stalling,
creeping and hard shifting on vehicles equipped with
automatic transaxles. Proceed to the Throttle Body Minimum Airflow pro-
cedures in Group 14.
IGNITION TIMING PROCEDUREÐ2.2L TBI, 2.5L
TBI, 2.5L MPI, AND 3.0L ENGINES
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING SETTING IGNITION
TIMING OR PERFORMING ANY TEST ON AN OPER-
ATING ENGINE.
Proper ignition timing is required to obtain optimum
engine performance. The distributor must be correctly
indexed to provide correct initial ignition timing. (1) Set the gearshift selector in park or neutral and
apply the parking brake. All lights and accessories
must be off. (2) If using a magnetic timing light, insert the
pickup probe into the open receptacle next to the
timing scale window. If a magnetic timing unit is not
available, use a conventional timing light connected to
the number one cylinder spark plug cable. Do not puncture cables, boots or nipples with
test probes. Always use proper adapters. Punc-
turing the spark plug cables with a probe will
damage the cables. The probe can separate the
conductor and cause high resistance. In addition
breaking the rubber insulation may permit sec-
ondary current to arc to ground. (3) Turn selector switch to the appropriate cylinder
position. (4) Start engine and run until operating tempera-
ture is obtained. (5) With the engine at normal operating tempera-
ture, connect the DRBII scan tool to the data link
connector (diagnostic connector). Access the State Dis-
play screen. Refer to the appropriate Powertrain Diag-
nostics Procedures Manual. If not using the DRBII
scan tool, disconnect the coolant temperature
sensor electrical connector. The electric radiator
fan will operate and the malfunction indicator lamp
(instrument panel Check Engine light) will turn on
after disconnecting the coolant sensor or starting the
DRBII scan tool procedure. (6) Aim Timing Light at timing scale (Fig. 7 or Fig.
8) or read magnetic timing unit. If flash occurs when
timing mark is before specified degree mark, timing is
advanced. To adjust, turn distributor housing in direc-
tion of rotor rotation. If flash occurs when timing mark is after specified
degree mark, timing is retarded. To adjust, turn dis-
tributor housing against direction of rotor rotation.
Refer to Vehicle Emission Control Information label for
correct timing specification. If timing is within 62É of
value specified on the label, proceed to step (8). If
outside specified tolerance, proceed to next step. (7) Loosen distributor hold-down arm screw
enough to rotate the distributor housing (Fig. 9 or
Fig. 6 Setting Spark Plug GapÐTypical
8D - 16 IGNITION SYSTEMS Ä