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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1626 - Theft Deterrent System Fuel Enable Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Ensure battery is fully charged. Crank engine. If engine cranks, go to next step. If engine does not crank, diagnose and repair TDS.
  3. Turn ignition off. Disconnect Vehicle Theft Deterrent (VTD) module connector. Turn ignition on. Using a DVOM, check voltage between VTD module harness connector ground and VTD fuel enable circuits. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 6).
  4. Turn ignition off. Reconnect VTD connector. Turn ignition on. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and VTD fuel enable circuit. If frequency is 40-60 Hz, go to next step. If frequency is not 40-60 Hz, go to step 8).
  5. Turn ignition off. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, see DIAGNOSTIC AIDS. If engine does not start, go to step 7).
  6. Check TDS fuel enable circuit for open, short to ground or short to battery voltage. Repair as necessary. After repairs, go to step 11). If no problem is found, go to next step.
  7. Check VTD fuel enable circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 11). If VTD fuel enable circuit connection at PCM is okay, go to step 9).
  8. Check for faulty connection at TDS module. Repair as necessary. After repairs, go to step 11). If connection is okay, go to step 10).
  9. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 11).
  10. Replace VTD module. After replacing module, go to next step.
  11. Clear DTCs. Turn ignition on and observe VTD FUEL DISABLE scan tool display. If scan tool displays INACTIVE, repair is complete. If scan tool does not display INACTIVE, return to step 2)
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