LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Oldsmobile >> 1997 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1406 - EGR Valve Pintle Position Circuit >> Diagnostic Procedures
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Diagnostic Procedures

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 3.8L article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Start engine and allow it to idle. Using scan tool, read EGR ACTUAL POS. If scan tool displays zero percent, go to next step. If scan tool does not display 0%, go to step 11).
  3. Turn ignition on. Select MISC TESTS on scan tool. Increment EGR valve from the 10 percent through the 100 percent positions while comparing the desired position with the actual position. If desired is close to actual, go to next step. If not, go to step 6).
  4. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using test light connected to ground, probe EGR ignition filter circuit at PCM connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 33)
  5. Turn ignition off. Reconnect PCM harness connector. Turn ignition on. Review and record FAIL RECORDS data. Operate vehicle within fail records conditions. Monitor SPECIFIC DTC for DTC P1406 until DTC test runs. If scan tool indicates this code failed this ignition, go to step 22). If not, see DIAGNOSTIC AIDS.
  6. Disconnect EGR valve harness connector. Connect a DVOM between EGR harness connector control and ignition feed circuits. Using scan tool, command EGR duty cycle to 100 percent position. If about battery voltage is present at 100 percent, go to step 17). If not, go to next step.
  7. Connect a test light between engine ground and EGR valve harness connector ignition feed circuit. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
  8. Check EGR valve ignition feed circuit fuse. If fuse is blown, locate and repair short to ground in ignition feed circuit. After repairs, go to step 34). If fuse is okay, go to step 24).
  9. Turn ignition off. Disconnect PCM connectors. Check EGR control circuit for open. If open is found, repair as necessary. After repairs, go to step 34). If no open is found, go to next step.
  10. Check for faulty EGR control circuit terminal connection at PCM. If connection is faulty, repair as necessary. After repairs, go to step 34). If connection is okay, go to step 32).
  11. Disconnect EGR valve harness connector. Using scan tool, read EGR ACTUAL POS. If scan tool displays zero percent, go to step 13). If scan tool does not display 0, go to next step.
  12. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check voltage between engine grounds and EGR pintle position circuit. If voltage is about zero volts, go to step 31). If voltage is not as specified, go to step 26).
  13. Connect a test light between battery voltage and EGR harness connector sensor ground circuit. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
  14. Check sensor ground circuit for faulty connection at PCM or open between PCM and EGR valve. If a problem is found, repair as necessary. After repairs, go to step 34). If no problem is found, go to step 32).
  15. Connect a test light between battery voltage and EGR harness connector control circuit. If test light illuminates, go to step 16). If test light does not illuminate, go to step 22).
  16. Turn ignition off. Disconnect PCM. Turn ignition on. Connect test light between battery voltage and EGR control circuit. If test light illuminates, go to step 28). If test light does not illuminate, go to step 30).
  17. Check voltage between EGR valve harness connector sensor ground and 5-volt reference circuits. If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 23).
  18. Connect test light between battery voltage and EGR valve harness connector pintle position circuit. If test light illuminates, go to step 21). If test light does not illuminate, go to next step.
  19. Connect a jumper wire between EGR valve connector 5-volt reference and pintle position circuits. Using scan tool, read EGR ACTUAL POS. If scan tool displays 100 percent, go to step 22). If scan tool does not display 100 percent, go to next step.
  20. Turn ignition off. Disconnect PCM connectors. Check pintle position circuit for open or faulty connection at PCM. If a problem is found, repair as necessary. After repairs, go to step 34). If no problem is found, go to step 32).
  21. Turn ignition off. Disconnect PCM connectors. Connect test light between battery voltage and pintle position circuit. If test light illuminates, go to step 29). If test light does not illuminate, go to step 30).
  22. Check for faulty connection at EGR valve. If faulty connection is found, repair as necessary. After repairs, go to step 33). If connection is okay, go to step 27).
  23. Check for open or short to ground in EGR 5-volt reference circuit. If a problem is found, go to step 34). If no problem is found, go to step 25).
  24. Locate and repair open ignition feed circuit. After repairs, go to step 34).
  25. Check EGR 5-volt reference circuit for faulty connection at PCM. If faulty connection is found, repair as necessary. After repairs, go to step 34). If connection is okay, go to step 32).
  26. Locate and repair short to voltage in pintle position circuit. After repairs, go to step 34).
  27. Replace EGR valve. After replacing EGR valve, go to step 34).
  28. Locate and repair short to ground in EGR control circuit. After repairs, go to step 34).
  29. Locate and repair short to ground in pintle position circuit. After repairs, go to step 34).
  30. Check pintle position circuit or EGR control circuit for short to sensor ground. Repair as necessary. After repairs, go to step 34). If circuits are okay, go to step 32).
  31. Check EGR pintle position circuit for short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 34). If circuit is okay, go to next step.
  32. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  33. Locate and repair open in EGR ignition filter circuit. After repairs, go to next step.
  34. Read and record FAIL RECORDS data for DTC P1406. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1406 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1406 FAILED THIS IGN, repair is complete.
scientia non olet · About LEMON Manuals