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.
    CAUTION: Support lower control arms so drive axles are in normal horizontal position or drive axles will be damaged.
  2. Turn ignition off. Raise and support drive axles. Start engine. With engine at idle, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to next step. If displayed vehicle speed is zero MPH, go to step  4 .
  3. 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. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to step  12 . If displayed vehicle speed is zero MPH, go to next step.
  4. Disconnect PCM harness connectors. Connect DVOM between VSS terminals. Rotate drive wheel by hand and note A/C voltage reading. If voltage reading is 0.5 volt or greater, go to next step. If voltage reading is not 0.5 volt or greater, go to step  7 .
  5. Check vehicle calibration code. If calibration is correct, go to step  13 . If calibration is incorrect, go to next step.
  6. Install proper or most current calibration code. After entering the calibration code, go to step  14 .
  7. Ensure ignition is off. Check resistance between VSS terminals. If resistance is greater than 1950 ohms, go to next step. If resistance is not greater than 1950 ohms, go to step  9 .
  8. Check for an open in VSS signal circuit. Repair as necessary. After repairs, go to step  14 . If circuit is okay, go to step  11 .
  9. If resistance reading in step  7 is 1300-1950 ohms, go to next step. If resistance is not 1300-1500 ohms, go to step  11 .
  10. Check for short to ground in VSS signal circuit. Also, check if VSS circuits are shorted together. Repair circuits as necessary. After repairs, go to step  14 . If circuit is okay, go to next step.
  11. Remove VSS. Check resistance between VSS terminals. If resistance is 1300-1950 ohms, go to step  13 . If resistance is not 1300-1950 ohms, go to next step.
  12. Replace VSS. After replacing sensor, go to step  14 .
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to 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 then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step  2 .
  15. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.
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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.