BASIC IGNITION SYSTEM CHECKS
DIS (EXCEPT 3.4L)
Spark
If factory tachometer is connected to coil tachometer terminal, disconnect tachometer before
performing tests. When removing spark plug wire from spark plug, twist and pull on boot. DO
NOT pull on wire.
1.
Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires
connected while checking for spark. Check spark plug wire resistance on suspect wires.
Resistance should be about 30,000 ohms.
2.
Ignition Coil Power Source
CAUTION: DO NOT insert DVOM leads into ignition coil connectors. Connector
terminals may be damaged. When using DVOM, ensure lead contacts
front edge of terminals only.
Turn ignition on. Check ignition positive voltage circuit of ignition control module for battery
voltage. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is not
present, check fuse for ignition control module circuit. If fuse is not open, check for open in circuit
between fuse and ignition control module.
Ignition Coil Test (2.2L, 4.3L, 5.0L, 5.7L, 6.5L & 7.4L)
Turn ignition off. Remove engine cover. Disconnect wiring from ignition coil and distributor
lead.
1.
Using DVOM, check for continuity between coil primary terminal and exterior case of coil
(ground). Replace ignition coil if continuity is present.
2.
Using DVOM, measure resistance between coil primary terminals. Replace ignition coil if
resistance is not 0.1 ohm.
3.
Using DVOM, measure coil secondary resistance. Replace ignition coil if resistance is not 5000
-25,000 ohms.
4.
5. Reconnect distributor lead and wiring to ignition coil. Install engine cover.
Ignition Coil Test (4.8L, 5.3L & 6.0L)
1. Turn ignition off. Disconnect wiring from ignition coils.
ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES -1999 Chevrolet Silvera. Page 1 of 4
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Using DVOM, measure resistance between ignition coil terminal "A" and ignition coil
mounting bracket. See appropriate wiring diagram in WIRING DIAGRAMS article. Replace
ignition coil if resistance is not 0-10,000 ohms.
2.
Using DVOM, measure coil secondary resistance. Replace ignition coil if resistance is not 3000
-7000 ohms.
3.
DIS (3.4L)
Electronic Ignition System Diagnosis (Primary Ignition Check)
Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD)
SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system
check, go to next step.
1.
If any Diagnostic Trouble Codes (DTCs) are present, diagnose DTCs. See appropriate SELFDIAGNOSTICS
article. If DTCs are not present, go to next step.
2.
Start engine. If a no start condition or hard-start condition is present, go to next step. If engine
starts okay, go to step 5.
3.
Turn ignition off. Disconnect Ignition Control Module (ICM) harness connector C2. Turn
ignition on. Using DVOM measure voltage between ground and ignition battery voltage circuit
at ICM harness connector C2. See appropriate wiring diagram in WIRING DIAGRAMS article.
If voltage is less than 10 volts, go to next step. If voltage is 10 volts or greater, go to NO
START-ENGINE CRANKS OKAY (3.4L) under NO START DIAGNOSIS.
4.
Drive vehicle and note driveability problems such as miss, stumble or hesitation. If driveability
problem is present, go to ELECTRONIC IGNITION SYSTEM DIAGNOSIS
(SECONDARY IGNITION CHECK). If driveability problem is not present, go to next step.
5.
If any other driveability problem is present, go to appropriate TROUBLE SHOOTING - NO
CODES article. If no other driveability problems are present, go to step 8.
6.
Check ELEK IGN fuse (10-amp), located in underhood junction block. If fuse is open, repair
short to ground in ignition battery voltage circuit between fuse and ICM. Replace fuse. If fuse is
okay, check for open in ignition battery voltage circuit. See appropriate wiring diagram in
WIRING DIAGRAMS article. Check for loose or corroded terminals and connections. Repair
as necessary. After repairs, go to next step. If circuit, terminals and connections are okay, go to
appropriate TROUBLE SHOOTING - NO CODES article.
7.
Operate vehicle within conditions in which problem occurred. If driveability problem is present,
perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD)
SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. If driveability problem is not
present, system is okay.
8.
Electronic Ignition System Diagnosis (Secondary Ignition Check)
Perform NO START DIAGNOSIS diagnosis. See NO START-ENGINE CRANKS OKAY
(3.4L) under NO START DIAGNOSIS. After performing no start diagnosis, go to next step.
1.
Install scan tool. Turn ignition on. If any Diagnostic Trouble Codes (DTCs) are present,
diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to
next step.
2.
Using scan tool, perform Fuel Injector Balance Test. See FUEL SYSTEM in appropriate
SYSTEM & COMPONENT TESTING article. Note cylinders with no engine speed or idle
3.
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quality change. If any cylinders were noted, go to next step. If no cylinders were noted, go to
step 17.
If 2 companion cylinders were noted, go to step 10. If 2 companion cylinders were not noted,
go to next step.
4.
Using DVOM, measure resistance of affected spark plug wire from end-to-end, and then from
one end to ground. If spark plug wire is shorted to ground, or resistance is greater than 7000
ohms, go to step 22. If spark plug wire is not shorted to ground, or resistance is 7000 ohms or
less, go to next step.
5.
Remove affected spark plug. If spark plug looks okay, go to next step. If spark plug does not
look okay, go to step 23.
6.
Using DVOM, measure resistance of affected spark plug. If resistance is less than 10,000 ohms,
go to next step. If resistance is 10,000 ohms or greater, go to step 23.
7.
Ground companion spark plug lead of affected cylinder. Install Spark Tester (J-26792). Crank
engine and note spark. If spark jumps tester gap, go to FUEL SYSTEM PRESSURE TEST
under BASIC FUEL SYSTEM CHECKS (GASOLINE). If spark does not jump tester gap, go
to next step.
8.
Ground affected spark plug lead. Install spark tester on companion cylinder of affected
cylinder. Crank engine and note spark. If spark jumps tester gap, go to step 25. If spark does not
jump tester gap, go to step 26.
9.
Ground one affected spark plug lead. Install spark tester on companion cylinder. Crank engine
and note spark. If spark jumps tester gap, go to step 12. If spark does not jump tester gap, go to
next step.
10.
Switch affected coil with another coil and perform Fuel Injector Balance Test. See FUEL
SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If fault follows
affected coil, go to step 25. If fault does not follow affected coil, go to step 26.
11.
Reinstall all spark plugs and wires. Start engine and check for visible/audible arcing. If ignition
system is arcing externally, go to step 27. If ignition system is not arcing externally, go to next
step.
12.
Ground other affected spark plug lead. Install spark tester on companion cylinder. Crank engine
and note spark. If spark jumps tester gap, go to next step. If spark does not jump tester gap, go
to step 25.
13.
Using DVOM, measure resistance of affected spark plug wire from end-to-end, and then from
one end to ground. If spark plug wire is shorted to ground, or resistance is greater than 7000
ohms, go to step 22. If spark plug wire is not shorted to ground, or resistance is 7000 ohms or
less, go to next step.
14.
Remove affected spark plugs and check for wear, damage or fouling. If both spark plugs are
okay, go to next step. If spark plugs are faulty, go to step 24.
15.
Using DVOM, measure resistance of affected spark plugs. If both spark plugs individually
measure less than 10,000 ohms, go to FUEL SYSTEM PRESSURE TEST under BASIC
FUEL SYSTEM CHECKS (GASOLINE). If both spark plugs individually measure 10,000
ohms or greater, go to step 24.
16.
Install spark tester on one spark plug wire and ground companion cylinder. Note spark with
engine idling. Repeat test for all spark plugs ensuring companion cylinder is grounded. If spark
jumps tester gap on all cylinders, go to FUEL SYSTEM PRESSURE TEST under BASIC
FUEL SYSTEM CHECKS (GASOLINE). If spark does not jump tester gap, go to next step.
17.
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Switch affected coil with another coil and repeat spark tester test on all 4 cylinders of switched
coils. If fault follows affected coil, go to step 25. If fault does not follow affected coil, go to
next step.
18.
Switch coils back to original location. Using DVOM, measure resistance of affected spark plug
wire from end-to-end, and then from one end to ground. If either spark plug wire is shorted to
ground, or resistance is greater than 7000 ohms, go to step 22. If either spark plug wire is not
shorted to ground, or resistance is 7000 ohms or less, go to next step.
19.
Remove affected spark plugs and check for wear, damage or fouling. If both spark plugs are
okay, go to next step. If spark plugs are faulty, go to step 24.
20.
Using DVOM, measure resistance of affected spark plugs. If both spark plugs individually
measure less than 10,000 ohms, go to step 26. If both spark plugs individually measure 10,000
ohms or greater, go to step 24.
21.
22. Replace spark plug wire. After repairs, go to step 28.
23. Replace spark plug. After repairs, go to step 28.
24. Replace affected spark plug. After repairs, go to step 28.
25. Replace affected coil. After repairs, go to step 28.
26. Replace ICM. After repairs, go to step 28.
27. Repair source of arcing. After repairs, go to next step.
Operate vehicle within conditions in which problem occurred. If driveability problem is present,
perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD)
SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. If driveability problem is not
present, system is okay.
28.
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Wednesday, September 2nd, 2020 AT 2:47 PM
