Diagnostic Procedures

1999 Chevrolet Cavalier Z24, 2D Convertible, AutomaticSECTION Diagnostic Procedures
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Check voltage on delivered torque circuit at PCM harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step  6.
  3. Using a DVOM, monitor current on delivered torque control circuit at PCM connector for at least 2 minutes. If DVOM reading is 1-500 milliamps, go to step  11. If DVOM reading is not 1-500 milliamps, go to next step.
  4. Turn ignition on. Check voltage between ground and delivered torque control circuit. If voltage reading is zero volts, go to step  10. If voltage reading is not zero volts, go to next step.
  5. Locate and repair short to voltage in delivered torque circuit. After repairs, go to step  16.
  6. Turn ignition off. Check ignition feed fuse for EBTCM. If fuse is open, go to next step. If fuse is okay, go to step  8.
  7. Locate and repair short to ground in ignition feed circuit. Replace fuse. After repairs, go to step  16.
  8. Disconnect EBTCM harness connector. Turn ignition on. Check voltage between ground and ignition feed circuit for EBTCM. If battery voltage is present, go to step. If battery voltage is not present, go to step  13.
  9. Check delivered torque control circuit for open or short to ground. Repair as necessary. After repairs, go to step  16. If circuit is okay, go to next step.
  10. Check delivered torque control circuit for poor connection to PCM or EBTCM. Repair as necessary. After repairs, go to step  16. If connections are okay, go to step  14.
  11. Turn ignition off. Reconnect PCM and EBTCM harness connectors. Turn ignition on. Using a test light, connect test light between delivered torque control circuit and ignition feed circuit. Using scan tool, cycle delivered torque output on and off. If test light flashes on and off, see DIAGNOSTIC AIDS . If test light does not flash, go to next step.
  12. Check delivered torque control circuit for poor connection at PCM. Repair as necessary. After repairs, go to step  16. If connections are okay, go to step  15.
  13. Locate and repair open in ignition feed circuit to EBTCM. After repairs, go to step  16.
  14. Replace EBTCM. After replacing EBTCM, go to step  16.
  15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  16. Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until this DTC test runs. If scan tool indicates that this DTC failed this ignition, repeat step  2. If scan tool does not indicate that this DTC failed this ignition, 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.