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Home >> Oldsmobile >> 1996 >> Eighty-Eight Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1374 - 3X Reference Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform 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. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see ENGINE DOES NOT START in BASIC TESTING article.
  3. Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1374 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1374 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
  4. Connect a test light to any injector harness connector. Turn ignition on. Connect repeatedly touch test light lead to 3X reference signal circuit while observing test light. If test light blinks, go to step 8). If test light does not flash, go to next step.
  5. Turn ignition off. Disconnect PCM. Check 3X reference signal circuit for open or short to ground. If a problem is found, go to step 11). If no problem is found, go to next step.
  6. Check for faulty 3X reference signal circuit connection at PCM. If a faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
  7. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 10).
  8. Check for faulty connections at ICM. If faulty connection is found, repair as necessary and go to step 11). If connections are okay, go to next step.
  9. Replace ICM and go to step 11).
  10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  11. Read and record FAIL RECORDS data for DTC P1374. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1374 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1374 FAILED THIS IGN, repair is complete.
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