SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1999MONTE CARLO LS, 3.8 KREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM - TESTS W/CODES - INTRODUCTIONSELF-DIAGNOSTIC SYSTEMDLC DIAGNOSIS OR NO SCAN TOOL DATA4.3L, 5.0L, 5.7L (VIN R) & 7.4L
1999 Chevrolet Monte Carlo LS, 3.8 K

4.3L, 5.0L, 5.7L (VIN R) & 7.4L

1999 Chevrolet Monte Carlo LS, 3.8 KSECTION 4.3L, 5.0L, 5.7L (VIN R) & 7.4L
NOTE: Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Connect scan tool to a known-good vehicle. If scan tool displays VCM data, go to step  4. If scan tool does not display VCM data, go to next step.
  3. Repair scan tool or scan tool cables.
  4. Reconnect scan tool to original vehicle. If scan tool powers up, go to next step. If scan tool does not power up, go to step  9.
  5. Using scan tool, select correct vehicle application. If vehicle information is correct, go to next step. If vehicle information is not correct, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
  6. Turn ignition on. Using scan tool, monitor class 2 serial data. If any modules on serial data circuit are communicating, go to step  13. If no modules communicate, go to next step.
  7. Turn ignition off. Disconnect components sharing serial data circuit, leaving VCM connected. Turn ignition on, with engine off. If scan tool displays VCM data, diagnose class 2 serial data circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If scan tool does not display VCM data, go to next step.
  8. Turn ignition off. Disconnect VCM harness connector C4. See appropriate wiring diagram in WIRING DIAGRAMS article. Using a test light connected to battery positive, probe class 2 serial data circuit at DLC (terminal No. 2). If test light illuminates, go to step  20. If test light does not illuminate, go to step  13.
  9. Using a test light connected to ground, probe battery positive feed circuit at DLC (terminal No. 16). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  12.
  10. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 4). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  16.
  11. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 5). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step  18. If test light does not illuminate, go to step  16.
  12. Inspect fuse associated with battery feed circuit. If fuse is open, go to step  14. If fuse is okay, go to step  15.
  13. Check for open or poor connection in class 2 serial data circuit. If a problem is found, go to step  17. If circuit is okay, go to step  19.
  14. Check for short to ground in battery feed circuit. Repair as necessary and replace fuse. After repairs, go to step  23.
  15. Repair open in battery feed circuit. After repairs, go to step  23.
  16. Repair open in DLC ground circuit. After repairs, go to step  23.
  17. Repair open or poor connection in class 2 serial data circuit. After repairs, go to step  23.
  18. Check for poor connections at DLC. If a problem is found, go to step  21. If connections are okay, see appropriate TROUBLE SHOOTING - NO CODES article.
  19. Check class 2 serial data circuit for poor connections at VCM and DLC. If a problem is found, go to step  21. If circuit connections are okay, go to step  22.
  20. Repair short to ground in class 2 serial data circuit. After repairs, go to step  23.
  21. Repair circuit as necessary. After repairs, go to step  23.
  22. Replace VCM. Perform VCM, Passlock® and CKP system relearn procedures. After repairs, go to next step.
  23. Using scan tool, check for DTCs. If any additional DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, system is okay.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.