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Home › Pontiac › 2003 › Aztek AWD › Repair and Diagnosis › Engine Performance › System › Engine Controls Self-Diagnostics › Diagnostic Tests › DTC P0480 Or P0481: Cooling Fan Relay Control Circuit › Diagnostic Procedures

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. Install a scan tool. Turn ignition on, with engine off. With a scan tool, command the Fans Low Speed ON and OFF. Does the cooling fan 1 relay turn ON and OFF with each command? If yes, go to next step. If no, go to step  4.
  3. Install a scan tool. Turn ignition on, with engine off. With a scan tool, command the Fans High Speed ON and OFF. Do the cooling fan 2 and the cooling fan 3 relays turn ON and OFF with each command? If yes, see DIAGNOSTIC AIDS . If no, go to step  6.
  4. Turn ignition off. Disconnect the cooling fan 1 relay. Turn ignition on, with engine off. Probe the battery positive voltage circuit of the cooling fan 1 relay with a test light that is connected to a good ground. Does the test light illuminate?
  5. Connect a test light between the control circuit of the cooling fan 1 relay and the battery positive voltage circuit of the cooling fan 1 relay. With a scan tool, command the Fans Low Speed ON and OFF. Does the test light turn ON and OFF with each command? If yes, go to step  12. If no, go to step  9.
  6. Turn ignition off. Disconnect the cooling fan 3 relay. Turn ignition on, with engine off. Probe the battery positive voltage circuit of the cooling fan 3 relay with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  16.
  7. Connect a test light between the control circuit of the cooling fan 3 relay and the battery positive voltage circuit of the cooling fan 3 relay. With scan tool, command the Fans High Speed ON and OFF. Does the test light turn ON and OFF with each command? If yes, go to step  14. If no, go to next step.
  8. Turn ignition off. Disconnect the cooling fan 2 relay. Turn ignition on, with engine off. Connect a test light between the control circuit of the cooling fan 2 relay and the battery positive voltage circuit of the cooling fan 2 relay. With a scan tool, command the Fans High Speed ON and OFF. Does the test light turn ON and OFF with each command? If yes, go to step  13. If no, go to next step.
  9. Does the test light remain illuminated with each command? If yes, go to step  11. If no, go to next step.
  10. Test the control circuit of the appropriate relay for a short to voltage or an open. Did you find and correct the condition? If yes, go to step  21. If no, go to step  15.
  11. Test the control circuit of the appropriate relay for a short to ground. Did you find and correct the condition? If yes, go to step  21. If no, go to step  15.
  12. Inspect for poor connections at the cooling fan 2 relay. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  13. Inspect for poor connections at the cooling fan 2 relay. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  14. Inspect for poor connections at the cooling fan 3 relay. Did you find and correct the condition? If yes, go to step  21. If no, go to step  19.
  15. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  21. If no, go to step  20.
  16. Repair the battery positive voltage circuit. After repairs, go to step  21.
  17. Replace cooling fan 1 relay. After replacing relay, go to step  21.
  18. Replace cooling fan 2 relay. After replacing relay, go to step  21.
  19. Replace cooling fan 3 relay. After replacing relay, 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. Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC reset? If yes, go to step  2. If no, system is okay.
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