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Home >> Pontiac >> 2003 >> Aztek AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0404: EGR Valve Open Pintle Position >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Is DTC P0403 or P0405 also set? If yes, diagnose affected DTC. See DTC P0403: EGR VALVE CONTROL CIRCUIT  or DTC P0405: EGR PINTLE POSITION CIRCUIT - LOW VOLTAGE  . If no, go to next step.
  3. Turn ignition on, with engine off. With scan tool, command the EGR valve from zero percent to 100 percent. Does the EGR position sensor remain within 15 percent of the desired EGR position at all commanded positions? If yes, go to next step. If no, go to step  5
  4. Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Operate the vehicle within the Conditions for Running DTC or within the observed parameters of the Freeze Frame/Failure Records. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  5. Turn ignition off. Disconnect the EGR valve. Turn ignition on, with engine off. With a scan tool, observe the EGR position sensor parameter. Does the scan tool indicate that the EGR position sensor is at 1 percent? If yes, go to next step. If no, go to step 11.
  6. Connect a test light between the 5-volt reference circuit of the EGR valve and the low reference circuit of the EGR valve. Does the test light illuminate? If yes, go to next step. If no, go to step  8.
  7. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the EGR valve and EGR valve position signal circuit. Observe the EGR Position Sensor parameter on scan tool. Is EGR position sensor parameter more than 99 percent? If yes, go to step  9. If no, go to step  13.
  8. Connect a test light between the 5-volt reference circuit of the EGR valve and a good ground. Does the test light illuminate? If yes, go to step  12. If no, go to step  14.
    9. NOTE: If the scan tool output control function times out, re-command the EGR valve to 100 percent before the next electrical measurement is taken.
  9. Command the EGR valve to 100 percent with scan tool. Measure the voltage from the EGR high control circuit to a good ground. Note the results in volts as "supply voltage". Connect a jumper wire between the EGR low control circuit and the corresponding terminal on the EGR valve. Connect a DVOM between the EGR high control circuit and the corresponding terminal on the EGR valve. Measure the note and current draw in amps. Remove the DVOM from the EGR high control circuit. Connect a jumper wire between the EGR high control circuit and the corresponding terminal on the EGR valve. Connect a DVOM in parallel between the EGR high control circuit and a good ground. Measure the voltage drop in volts and note as "load voltage drop". Subtract the load voltage drop from the supply voltage then divide the answer by the current draw. The result is the amount of resistance in the EGR high control circuit. Is the calculated resistance more than 3 ohms? If yes, go to step  15. If no, go to next step.
    10. NOTE: If the scan tool output control function times out, re-command the EGR valve to 100 percent before the next electrical measurement is taken.
  10. Connect a DVOM in parallel between the EGR low control circuit and a good ground. Measure the voltage drop in volts and not as "low control voltage drop". Divide the low control voltage drop by the current draw. The result is the amount of resistance in the low control circuit. Is the calculated resistance more than 3 ohms? If yes, go to step  16. If no, go to step  17.
  11. Test the EGR valve position signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  12. Test the low reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  13. Test the EGR valve position signal circuit for an open, short to ground, or high resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  14. Test the 5-volt reference circuit of the EGR position sensor for an open, a short to ground, or a short to voltage. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  15. Test the high control circuit of the EGR valve for resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  16. Test the low control circuit of the EGR valve for resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  17. Test for an intermittent and for a poor connection at the EGR valve. Did you find and correct the condition? If yes, go to step  21. If no, go to step  19.
  18. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  21. If no, go to step  20.
  19. Replace EGR valve. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  21.
  20. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  21. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  22. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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