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Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
    NOTE: If DTC P0403 or P0405 is set, diagnose affected DTC(s) first. See DTC P0403: EGR SOLENOID CONTROL CIRCUIT  or DTC P0405: EGR POSITION SENSOR CIRCUIT LOW VOLTAGE .
  2. Ensure ignition is on. Using scan tool, command EGR valve from zero to 100 percent. If EGR position sensor remains within 20 percent of desired EGR position at all commanded positions, go to next step. If EGR position sensor does not remain within 20 percent of desired EGR position at all commanded positions, go to step  4.
  3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. See CONDITIONS FOR RUNNING DTC . If DTC resets, go to next step. If DTC does not reset, see DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect EGR valve connector. Turn ignition on. Probe EGR solenoid high control circuit with a test light connected to a good ground. With scan tool, command the EGR between 0 percent and 10 percent. Does the test light turn ON and OFF with each command? If yes, go to next step. If no, go to step  13.
  5. With a scan tool, observe EGR position sensor parameter. Does scan tool indicate that the EGR position sensor is at zero percent? If yes, go to next step. If no, go to step  9.
  6. Using a Digital Multimeter (DMM), measure voltage from the 5-volt reference circuit of EGR position sensor to the low reference circuit of EGR position sensor. Does the DMM display about 5 volts? If yes, go to next step. If no, go to step  8.
    7. NOTE: If the fuse blows, locate and repair the short to ground in the signal circuit.
  7. Connect a fused jumper between EGR position sensor harness connector 5-volt reference and position signal circuits. Does scan tool indicate that the EGR position sensor is about 100 percent? If yes, go to step  14. If no, go to step  11.
  8. Measure the voltage from the 5-volt reference circuit of the EGR position sensor to a good ground. Does the DMM display about 5 volts? If yes, go to step  10. If no, go to step  12.
  9. Test the EGR valve position signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  10. Test the low reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  11. Test the EGR valve position signal circuit for high resistance or a high resistance short to ground. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  12. 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  18. If no, go to step  15.
  13. Test the EGR solenoid high control circuit for an open or short to ground. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  14. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step  18. If connector is okay, go to step  16.
  15. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step  18. If connectors are okay, go to step  17.
  16. Replace EGR valve. After repairs, go to step  18.
  17. Replace PCM. Program replacement PCM. See PROGRAMMING . After repairs, go to next step.
  18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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