LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1999 >> Forward Control 4.3 W, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> Basic Ignition System Checks >> Dis (3.4L) >> Electronic Ignition System Diagnosis (Primary Ignition Check)

Electronic Ignition System Diagnosis (Primary Ignition Check)

  1. 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.
  2. If any Diagnostic Trouble Codes (DTCs) are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
scientia non olet · About LEMON Manuals