Diagnostic Procedures

2000 Chevrolet Cavalier Base, 2D Coupe, Automatic, 4T40E/MN4SECTION Diagnostic Procedures
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, go to next step. If engine will not start, see NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  3. Turn ignition off. Remove air cleaner outlet resonator. Disconnect all injector connectors. Install an injector test light on No. 1 injector harness connector. Crank engine and observe test light. Check remaining fuel injectors. If test light flashes on all injectors, perform injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash on all injectors, go to next step.
  4. If test light did not flash in step  3 but was on steady, go to next step. If test light did not flash in step  3 and was off, go to step  7 .
  5. Remove injector test light from affected circuit. Turn ignition off. Disconnect PCM harness connector containing affected fuel injector circuit. Using a test light connected to battery positive, probe affected fuel injector driver circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step  12 .
  6. Repair short to ground in fuel injector driver circuit. After repairs, go to step  13 .
  7. Using test light connected to ground, probe ignition feed circuit terminal at affected fuel injector harness connector. Crank engine. If test light illuminates, go to next step. If test light does not illuminate, go to step  9 .
  8. With test light still connected to ground, probe fuel injector driver circuit terminal at affected injector harness connector. Crank engine. If test light illuminates, go to step  11 . If test light does not illuminate, go to step  10 .
  9. Turn ignition off. Repair open or poor connection in ignition feed circuit. After repairs, go to step  13 .
  10. Turn ignition off. Check for open or faulty connection in fuel injector driver circuit. If a problem is found, go to step  13 . If circuit is okay, go to step  12 .
  11. Turn ignition off. Check for short to voltage in fuel injector driver circuit. Repair as necessary. After repairs, go to step  13 . If circuit is okay, go to next step.
  12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  13. Reconnect all fuel injector harness connectors. Using scan tool, clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function, and then enter DTC which was set. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2 .
  14. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, system is okay.
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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.