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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 107 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P0418: Secondary Air Injection Pump Relay Control Circuit >> Diagnostic Procedures

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.
  2. Turn ignition on. Using scan tool, command AIR pump relay on and off. Does the relay turn ON and OFF with each command? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  3. Turn ignition off. Disconnect AIR pump relay. Turn ignition on. Using a test light connected to ground, probe AIR pump relay coil feed circuit at AIR pump relay harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  10.
  4. Connect a test light between control and feed circuits at AIR pump relay harness connector. Using scan tool, command AIR pump and AIR solenoid on and off. If test light turns on and off with each command, go to step  8. If test light does not turn on and off with each command, go to next step.
  5. If test light remains illuminated with each command, go to step  7. If test light does not remain illuminated with each command, go to next step.
  6. Test the control circuit for a short to voltage or an open. If any problems are found, repair as necessary. After repairs, go to step  13. If no problems are found, go to step  9.
    7. NOTE: After repair is made, reconnect all devices and replace all open fuses. Turn ignition on, with engine off. Use scan tool to command AIR pump and solenoid ON and OFF. If pump does not operate, replace pump.
  7. Test the control circuit for a short to ground. Did you find and correct the condition? If yes, go to step  13. If no, go to step  9.
  8. Check for poor connections at AIR pump relay connector. Repair connector as necessary. After repairs, go to step  13. If connector is okay, go to step  11.
  9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step  13. If connectors are okay. go to step  12.
  10. Repair open or short to ground in feed circuit. After repairs, go to step  13.
  11. Replace AIR pump relay. After repairs, go to step  13.
  12. Replace PCM. Program replacement PCM. See PROGRAMMING . After repairs, go to next step.
  13. 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.
  14. 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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