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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 73 (Engine Controls Self-Diagnostics - 5.7L Corvette) >> Diagnostic Tests >> DTC P0418: Air Pump Relay Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Chevrolet Corvette. 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, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Connect a scan tool. Turn ON the ignition, with the engine OFF. Command the AIR pump relay ON and OFF with a scan tool. Does the relay turn ON and OFF with each command? If yes, go to next step. If no, go to step  4.
  3. Review the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Does the DTC set? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn OFF the ignition. Remove the AIR pump relay. Turn ON the ignition, with the engine OFF. Test the ignition 1 voltage circuit at the relay for an open with a test lamp connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  11.
  5. Connect a test lamp between the following 2 circuits of the AIR pump relay:
    • The AIR pump relay control circuit.
    • The ignition 1 voltage circuit.

    Command the relay ON and OFF with a scan tool. Does the test lamp turn ON and OFF with each command? If yes, go to step  9. If no, go to next step.

  6. Does the test lamp remain illuminated with each command? If yes, go to step  8. If no, go to next step.
  7. Test the AIR pump relay control circuit for a short to voltage, or for an open. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test the AIR pump relay control circuit for a short to ground. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  9. Inspect for poor connections at the AIR pump relay. Repair conditions as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Inspect for poor connections at the PCM. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair the ignition 1 voltage circuit of the AIR pump relay. After repairs, go to step  14.
  12. Replace the AIR pump relay. After repairs, go to step  14.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. 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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