1993 CHEVROLET DYNASTY charging

STARTER CONTROL CIRCUIT TESTS
The starter control circuit has:
² Starter solenoid
² Starter relay (Fig. 2)
² Neutral starting and back-up switch with auto-
matic transmissions
² Clutch pedal mounted starter interlock switch
with manual transmissions
² Ignition switch
² Battery
² All related wiring and connections
CAUTION: Before performing any starter tests, the
ignition system must be disabled.
² VEHICLES EQUIPPED WITH A CONVEN-
TIONAL DISTRIBUTOR: Disconnect coil wire from
distributor cap center tower. Secure wire to a good
ground to prevent engine from starting (Fig. 6).
² VEHICLES EQUIPPED WITH DIRECT IGNI-
TION SYSTEM: Unplug the coils electrical connector
(Fig. 7).
STARTER SOLENOID 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 this starter solenoid test BEFORE per-
forming the starter relay test. (3) Raise the vehicle.
(4) Perform a visual inspection of the starter/
starter solenoid for corrosion, loose connections or
faulty wiring. (5) Lower the vehicle.
(6) Locate the starter relay as follows:
² On AC, AG, AJ and AY Bodies the relay is located
in the Power Distribution Center. This Center is mounted near the front of the left front strut tower
(Fig. 13). The position of the starter relay within this
Center will be shown on the Center cover.
² On AA/AP Bodies the relay is located on the front
of the left front strut tower (Fig. 14).
(7) Remove the starter relay from the connector.
(8) Connect a remote starter switch or a jumper
wire between the battery positive post and terminal
87 on the starter relay connector. To decide the
starter relay terminal numbers, refer to the Starter
Relay Tests.
² If engine now cranks, starter/starter solenoid is
good. Go to the starter relay test.
² If engine does not crank with this test, or solenoid
chatters, check wiring and connectors from starter
Fig. 12 Test Positive Battery Cable Resistance
Fig. 13 Starter Relay LocationÐAC, AG, AJ, and AY Bodies
Fig. 14 Starter Relay LocationÐAA/AP Body
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 15

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

Fig. 15 Starter Relay Tests
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 17

Fig. 16 Field Coil Wire TerminalÐBosch
Fig. 17 Field Coil Wire TerminalÐNippondenso
Fig. 18 Continuity Test Between Solenoid Terminal and Field Coil TerminalÐBosch
Fig. 19 Continuity Test Between Solenoid Terminaland Field Coil TerminalÐNippondenso
Fig. 20 Continuity Test Between Solenoid Terminal and Solenoid Case ÐBosch
Fig. 21 Continuity Test Between Solenoid Terminaland Solenoid Case ÐNippondenso
8A - 18 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä

GENERATOR TEST PROCEDURES ON VEHICLE INDEX
page page
Charging System Diagnostics (Fig. 1) ......... 19
Current Output Test ...................... 19 Output Wire Resistance Test
................ 19
CHARGING SYSTEM DIAGNOSTICS (Fig. 1)
OUTPUT WIRE RESISTANCE TEST
The generator output wire resistance test shows
the amount of voltage drop across the generator out-
put wire between the generator B+ terminal and the
positive battery post.
PREPARATION
Before starting test, make sure the vehicle has a
fully charged battery. Tests and procedures to check
for a fully charged battery is shown in the Battery
section. (1) Turn the ignition switch OFF.
(2) Disconnect battery NEGATIVE cable.
(3) Disconnect the generator B+ output wire from
the generator output battery terminal (Fig. 2). (4) Connect a 0-150 ampere scale (DC) ammeter in
series between B+ terminal and output wire (Fig. 2
and 3). Connect positive lead to B+ terminal, and
negative lead to output wire. (5) Using o-18 volt scale voltmeter, connect the
positive lead to the disconnected (B+) output wire
(Fig. 2). Connect the negative lead to positive battery
post. (6) Remove fresh air hose between Powertrain
Control Module and air cleaner if necessary. (7) Connect jumper wire between a good ground
and K20 circuit terminal at the back of the genera-
tor.
CAUTION: Do not connect the A142 circuit terminal
(Fig. 2) to ground the Fusible link will burn.
(8) Connect an engine tachometer and connect bat-
tery negative cable. (10) Connect a volt/amp tester equipped with a
variable carbon pile rheostat between battery termi-
nals (Fig. 4).
Caution: Be sure the carbon pile is in OFF position
before connecting leads.
TEST
(1) Start engine. Immediately after starting, re-
duce engine speed to idle. (2) Adjust engine speed and carbon pile to main-
tain 20 amperes flowing in the circuit. Observe volt-
meter reading. Voltmeter reading should not exceed
0.5 volts.
RESULTS
If a higher voltage drop is shown, inspect, clean
and tighten all connections between generator B+
terminal and battery positive post. A voltage drop
test may be performed at each connection to locate a
connection with excessive resistance. If resistance
tests are satisfactory, reduce engine speed, turn off
carbon pile, and turn off ignition switch. (1) Disconnect battery negative cable.
(2) Remove test ammeter, voltmeter, carbon pile,
and tachometer. (3) Remove jumper wire.
(4) Connect generator output wire to generator B+
terminal. (5) Connect battery negative cable.
(6) Connect fresh air hose between Powertrain
Control Module and air cleaner if removed.
CURRENT OUTPUT TEST
The current output test decides whether the gener-
ator can deliver its rated current output. For gener-
ator identification and output amperage
specifications, refer to Generator Specifications. For generator maximum voltage at individual tem-
peratures, refer to Generator Output Voltage Specifi-
cations.
PREPARATION
Before starting any tests, make sure the vehicle
has a fully charged battery. Tests and procedures to
check for a fully charged battery is shown in Battery
section. (1) Disconnect battery negative cable.
(2) Disconnect output wire at the B+ terminal
(Figs. 2 and 5). (3) Connect a 0-150 ampere scale (DC) ammeter in
series between the B+ terminal and output wire.
Connect Positive lead to B+ terminal and negative
lead to output wire. (4) Using 0-18 voltmeter, connect positive lead to
B+ terminal (Figs. 2 and 5). Connect negative lead
to a good ground.
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 19

Fig. 1 Charging Diagnostics
8A - 20 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä

(5) Connect an engine tachometer and connect bat-
tery negative cable. (6) Connect a volt/amp tester equipped with a vari-
able carbon pile rheostat between battery terminals
(Fig. 6). Be sure carbon pile is in OFF position before
connecting leads. (7) Remove fresh air hose between Powertrain
Control Module computer and air cleaner if neces-
sary. (8) Full field the generator. Connect a jumper wire
between a good ground and K20 circuit terminal at
the back of the generator (Figs. 2 and 5).
CAUTION: Do not connect the A142 circuit terminal
(Fig. 2) to ground. Fusible link will burn.
TEST
(1) Start the engine. Immediately after starting,
reduce engine speed to idle.
Fig. 2 Generator Wiring Connections
Fig. 3 Generator Output Wire Resistance Test
Fig. 4 Volt/Amp Tester Connections
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 21

(2) Adjust the carbon pile and engine speed in
steps until an engine speed of 1250 rpm, and a volt-
meter reading of 15 volts is obtained.
CAUTION: Do not allow the battery voltage to ex-
ceed 16 volts. (3) The generator amperage must meet the output
requirements for the particular generator being
tested. Refer to Generator Specifications for genera-
tor identification and amperage outputs.
RESULTS
(1) If amperage reading is less than specified, and
generator output wire resistance is not found exces-
sive from the previous tests, generator should be re-
placed. Refer to Group 8B, Battery/Starter/Generator
Service, Generator Replacement. These generators
are not intended to be disassembled for service. It
must be replaced as an assembly. (2) After current output test is completed, reduce
engine speed, turn off carbon pile, and turn off igni-
tion switch. (3) Disconnect battery negative cable.
(4) Remove test ammeter, voltmeter, tachometer
and carbon pile. (5) Remove jumper wire between K20 circuit ter-
minal and ground. (6) Connect output wire to B+ terminal.
(7) Connect negative battery cable.
(8) Connect fresh air hose between powertrain con-
trol module and air cleaner if removed.
Fig. 5 Generator Current Output Test
Fig. 6 Volt/Amp Tester Connections
8A - 22 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä