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HOMESERVICE MANUALSCHEVROLET2001CAVALIER LS, 2.4 TREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 86 (ENGINE CONTROLS SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0418: AIR PUMP RELAY CONTROL CIRCUITDIAGNOSTIC PROCEDURES
2001 Chevrolet Cavalier LS, 2.4 T

Diagnostic Procedures

2001 Chevrolet Cavalier LS, 2.4 TSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 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. Are DTCs P0102, P0412, P0443, P0449, P0740, P0785, P1860 also set? If yes, go to step  13. If no, go to next step.
  3. Turn ignition ON, with engine OFF. Command AIR pump relay ON and OFF with a scan tool. Listen for a click when the relay operates. Repeat the commands as necessary. Does AIR pump relay turn ON and OFF with each command? If yes, go to next step. If no, go to step  5.
  4. Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  5. Turn ignition OFF. Remove AIR pump relay. Turn ignition ON, with engine OFF. Test the AIR pump relay ignition 1 voltage circuit for an open with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  12.
  6. Connect a test light between the AIR pump relay control circuit and the AIR relay ignition 1 voltage circuit. Command AIR pump relay ON and OFF with a scan tool. Does the test light turn ON and OFF? If yes, go to step  10. If no, go to next step.
  7. Does the test light remain illuminated with each command ON and OFF? If yes, go to step  9. If no, go to next step.
    8. NOTE: The AIR pump may be damaged if the control circuit is shorted to voltage.
  8. Test the AIR pump relay control circuit for a short to voltage, or for an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
    9. NOTE: The AIR pump may be damaged if the control circuit is shorted to ground.
  9. Test the AIR pump relay control circuit for a short to ground. Did you find and correct the condition? If yes, go to step  14. If no, go to step  17.
  10. Test for an intermittent and/or poor connections at the AIR pump relay. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  11. Test for an intermittent and/or poor connections at the PCM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  12. Repair the open circuit in the AIR pump relay ignition 1 voltage circuit. Did you complete the repair? If yes, go to step  18.
  13. Repair the short to ground in the ignition 1 voltage circuit or related components. Replace ENG IGN 1 fuse as necessary. Did you complete the repair? If yes, go to step  18.
  14. Ensure that all components are installed and all connections are secured. Command AIR pump relay ON and OFF with a scan tool. Does AIR pump turn ON and OFF when commanded with a scan tool? If yes, go to step  18
  15. Replace AIR pump. See SECONDARY AIR INJECTION PUMP under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION - CORVETTE article. Replace AIR pump fuse as necessary. Did you complete the replacement? If yes, go to step  18.
  16. Replace AIR relay. Did you complete the replacement? If yes, go to step  18.
  17. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to next step.
    18. NOTE: The scan tool status for this DTC will not report a pass. The scan tool will only display if the diagnostic test fails. The repair is not complete if the scan tool indicates that the diagnostic test ran and failed.
  18. 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 the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle ? If yes, go to step  2. If no, go to next step.
  19. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.