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DTC P0505: Idle Air Control Motor Circuits: Testing

  1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP is displayed and equal to zero, go to next step. If GOOD TRIP is not displayed and equal to zero, go to step  22 .
  2. Start engine and let it idle. Disconnect IAC motor harness connector. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure voltage between ground and IAC driver circuit No. 1 (Gray/Red wire) at IAC motor harness connector. If voltage is more than 5 volts, go to next step. If voltage is 5 volts or less, go to step  19 .
  3. Measure voltage between ground and IAC driver circuit No. 2 (Yellow/Black wire) at IAC motor harness connector. If voltage is more than 5 volts, go to next step. If voltage is 5 volts or less, go to step  16 .
  4. Measure voltage between ground and IAC driver circuit No. 3 (Brown/White wire) at IAC motor harness connector. If voltage is more than 5 volts, go to next step. If voltage is 5 volts or less, go to step  13 .
  5. Measure voltage between ground and IAC driver circuit No. 4 (Violet/Black wire) at IAC motor harness connector. If voltage is more than 5 volts, go to next step. If voltage is 5 volts or less, go to step  10 .
  6. Turn ignition off. Disconnect PCM harness connectors. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure resistance between IAC driver circuit No. 1 (Gray/Red wire) and each other IAC driver circuit at IAC motor harness connector. If resistance is 5 ohms or more between all circuits, go to next step. If resistance is less than 5 ohms between any circuits, repair short between IAC driver circuits.
  7. Measure resistance between IAC driver circuit No. 2 (Yellow/Black wire) and No. 3 (Brown/White wire) then No. 4 (Violet/Black wire) at IAC motor harness connector. If resistance is 5 ohms or more between all circuits, go to next step. If resistance is less than 5 ohms between any circuits, repair short between IAC driver circuits.
  8. Measure resistance IAC driver circuit No. 3 (Brown/White wire) and No. 4 (Violet/Black wire) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short between IAC driver circuits.
  9. If no other possible causes are remaining, replace IAC motor.
  10. Turn ignition off. Disconnect PCM harness connectors. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure resistance of IAC driver circuit No. 4 (Violet/Black wire) between IAC motor harness connector and terminal No. 58 at PCM C2 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Violet/Black wire.
  11. Measure resistance between ground and IAC driver circuit No. 4 (Violet/Black wire) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Violet/Black wire.
  12. If no other possible causes are remaining, replace PCM.
  13. Turn ignition off. Disconnect PCM harness connectors. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure resistance of IAC driver circuit No. 3 (Brown/White wire) between IAC motor harness connector and terminal No. 48 at PCM C2 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/White wire.
  14. Measure resistance between ground and IAC driver circuit No. 3 (Brown/White wire) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/White wire.
  15. If no other possible causes are remaining, replace PCM.
  16. Turn ignition off. Disconnect PCM harness connectors. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure resistance of IAC driver circuit No. 2 (Yellow/Black wire) between IAC motor harness connector and terminal No. 49 at PCM C2 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Yellow/Black wire.
  17. Measure resistance between ground and IAC driver circuit No. 2 (Yellow/Black wire) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Yellow/Black wire.
  18. If no other possible causes are remaining, replace PCM.
  19. Turn ignition off. Disconnect PCM harness connectors. See Figure . Inspect connectors for damage or poor connections. Clean or repair connectors as necessary. If connectors are okay, measure resistance of IAC driver circuit No. 1 (Gray/Red wire) between IAC motor harness connector and terminal No. 57 at PCM C2 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/Red wire.
  20. Measure resistance between ground and IAC driver circuit No. 1 (Gray/Red wire) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray/Red wire.
  21. If no other possible causes are remaining, replace PCM.
  22. Start engine. Using scan tool, select SYSTEMS TEST, then IAC WIGGLE TEST. Idle speed should increase and decrease with scan tool display. Wiggle wiring harness between IAC motor and PCM. If IAC motor does not stop operating, go to next step. If IAC motor stops operating at any time, repair wiring harness or connectors where wiggling causes IAC motor to stop operating.
  23. Turn ignition off. Visually inspect wiring harness and connectors between IAC motor and PCM. If a problem is found, repair as necessary. If no problems are found, test is complete.
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