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Home › Isuzu › 1996 › Trooper LS, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes › Circuit Tests › DTC P1406 - EGR Valve Pintle Position Circuit

DTC P1406 - EGR Valve Pintle Position Circuit

  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. Turn engine on 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 zero percent, go to step 10).
  3. Using scan tool, select MISC. TESTS and command EGR duty cycle through 25, 50, 75 and 100 percent positions. Compare scan tool display EGR DESIRED POSITION and EGR ACTUAL POS. If both readings are close, go to next. If readings are not close, go to step 5).
  4. Turn ignition on, engine off. 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 P1406 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1406 FAILED THIS IGN, check for an intermittent problem. See TESTS W/O CODES article.
  5. 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 25, 50, 75 and 100 percent position while observing voltage reading on DVOM. If readings are approximately 3 volts at 25 percent and increases to battery voltage at 100 percent, go to step 16). If voltage does not increase as specified, go to next step.
  6. Turn ignition on. Connect a test light between engine ground and EGR valve harness connector ignition feed circuit. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
  7. Check EGR valve ignition feed circuit fuse. If fuse is blown, locate and repair short to ground in ignition feed circuit. Retest system. If fuse is okay, go to step 23).
  8. Turn ignition off. Disconnect PCM connectors. Check EGR control circuit for an open. If an open is found, repair as necessary. Retest system. If no open is found, go to next step.
  9. Check for faulty EGR control circuit connection at PCM. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 29).
  10. Disconnect EGR valve harness connector. Using scan tool, read EGR ACTUAL POS. If scan tool displays zero percent, go to step 12). If scan tool does not display zero percent, go to next step.
  11. 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 29). If voltage is not as specified, go to step 26).
  12. Connect a test light between battery voltage terminal and EGR harness connector sensor ground circuit. If test light illuminates, go to step 14). If test light does not illuminate, go to next step.
  13. Check sensor ground circuit for faulty connection at PCM or an open between PCM and EGR valve. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 29).
  14. Connect a test light between battery voltage terminal and EGR harness connector control circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 26).
  15. Turn ignition off. Disconnect PCM. Turn ignition on. Connect test light between battery voltage terminal and EGR control circuit. If test light illuminates, go to step 27). If test light does not illuminate, go to step 29).
  16. 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 22).
  17. Connect test light between battery voltage terminal and EGR valve harness connector pintle position circuit. If test light illuminates, go to step 20). If test light does not illuminate, go to next step.
  18. Connect a jumper wire between EGR valve connector 5-volt reference and pintle position circuits. Using scan tool, read EGR DUTY CYCLE. If scan tool displays 100 percent, go to step 21). If scan tool does not display 100 percent, go to next step.
  19. 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. Retest system. If no problem is found, go tostep 29).
  20. Turn ignition off. Disconnect PCM connectors. Connect test light between battery voltage terminal and pintle position circuit. If test light illuminates, go to step 28). If test light does not illuminate, go tostep 29).
  21. Check for faulty connection at EGR valve. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 26).
  22. Check for open or short to ground in EGR 5-volt reference circuit. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 24).
  23. Locate and repair open ignition feed circuit. Retest system.
  24. Check EGR 5-volt reference circuit for faulty connection at PCM. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step 29).
  25. Locate and repair short to voltage in pintle position circuit. Retest system.
  26. Replace EGR valve. Retest system.
  27. Locate and repair short to ground in EGR control circuit. Retest system.
  28. Locate and repair short to ground in pintle position circuit. Retest system.
  29. Replace PCM. Retest system.
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