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DTC P0505: Idle Air Control Motor Circuits

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Monitored with ignition on and battery voltage more than 11.5 volts. Set condition is when PCM senses short to ground or battery voltage on any 4 IAC driver circuits for 2.75 seconds while IAC motor is active. Possible causes are: IAC driver circuit shorted to ground, IAC driver circuit open, damaged wiring or connector, IAC motor defective, IAC driver circuit shorted to another IAC driver circuit, intermittent wiring harness failure or PCM defective.
  1. Start engine and idle. If engine will not idle, hold throttle open slightly to keep engine running. Using scan tool, actuate Idle Air Control (IAC) motor to 1400 RPM. Release throttle if holding open. Engine speed should be 1300-1500 RPM. If engine speed is within specification, go to next step. If engine speed is not within specification, go to step  23 .
  2. Using scan tool, actuate IAC motor to 900 RPM. Engine speed should be 800-1000 RPM. If engine speed is within specification, go to next step. If engine speed is not within specification, go to step  23 .
  3. With engine idling, using scan tool, perform IAC wiggle test. Idle speed should raise and lower with scan tool display. If engine speed raised and lowered with scan tool display, go to next step. If engine speed did not raise and lower with scan tool display, go to step  6 .
  4. Turn ignition off. Inspect wiring and connectors for damage. If wiring and connectors are okay, go to next step. If wiring and connectors are not okay, repair or replace as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  5. Start engine. Using scan tool in systems tests, perform IAC wiggle test. Wiggle wiring harness between IAC motor and Powertrain Control Module (PCM) connectors. Observe IAC motor for any interruptions in operation. If IAC did not stop operating at any time, test is complete. If IAC stopped operating at any time, repair wiring harness as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  6. Turn ignition off. Inspect wiring and connectors for damage. If wiring and connectors are okay, go to next step. If wiring and connectors are not okay, repair or replace as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  7. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 1 (Gray/Red wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  18 .
  8. Turn ignition off. Using a DVOM, check resistance of IAC motor connector driver circuit No. 4 (Violet/Black wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair driver circuit No. 4 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  9. Turn ignition off. Using a DVOM, check resistance of IAC motor connector driver circuit No. 1 (Gray/Red wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair driver circuit No. 1 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  10. Start engine and idle. Using a DVOM, check voltage of IAC motor connector driver circuit No. 2. If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  14 .
  11. Turn ignition off. Using a DVOM, check resistance of IAC motor connector driver circuit No. 2 (Yellow/Black wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  12. Turn ignition off. Using a DVOM, check resistance of IAC motor connector driver circuit No. 3 (Brown/White wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  13. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 3 (Brown/White wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  40 .
  14. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 2 (Yellow/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  15. Using a DVOM, check resistance between IAC motor connector driver circuit No. 3 (Brown/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  16. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 2 between IAC motor connector (Yellow/Black wire) and PCM connector C2 terminal No. 49 (Yellow/Black wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 2. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  17. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  18. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 4 (Violet/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 4 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  19. Using a DVOM, check resistance between IAC motor connector driver circuit No. 1 (Gray/Red wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 1 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  20. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 1 between IAC motor connector (Gray/Red wire) and PCM connector C2 terminal No. 57 (Gray/Red wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 1. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  21. Using a DVOM, check resistance between IAC motor connector driver circuit No. 2 (Yellow/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  22. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  23. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 1 (Gray/Red wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  49 .
  24. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 4 (Violet/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 4 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  25. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 2 (Yellow/Black wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  43 .
  26. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 1 (Gray/Red wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 1 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  27. Using a DVOM, check resistance between IAC motor connector driver circuit No. 2 (Yellow/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  28. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 3 (Brown/White wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step  39 .
  29. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 3 (Brown/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  30. Start engine and idle. Disconnect IAC motor connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check voltage of IAC motor connector driver circuit No. 4 (Violet/Black wire). If voltage is more than 5 volts at any time, go to next step. If voltage is not more than 5 volts at any time, go to step 36.
  31. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  32. Using a DVOM, check resistance between the following circuits at IAC motor connector. Record resistance readings.
    • IAC motor connector driver No. 1 (Gray/Red wire) and driver No. 2 (Yellow/Black wire).
    • IAC motor connector driver No. 1 (Gray/Red wire) and driver No. 3 (Brown/White wire).
    • IAC motor connector driver No. 1 (Gray/Red wire) and driver No. 4 (Violet/Black wire).

    If resistance between any 2 wires was less than 5 ohms, repair those wires for shorting together. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  . If resistance between all pairs of wires was 5 ohms or more, go to next step.

  33. Using a DVOM, check resistance between the following circuits at IAC motor connector. Record resistance readings..
    • IAC motor connector driver No. 2 (Yellow/Black wire) and driver No. 3 (Brown/White wire).
    • IAC motor connector driver No. 2 (Yellow/Black wire) and driver No. 4 (Violet/Black wire).

    If resistance between any 2 wires was less than 5 ohms, repair those wires for shorting together. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  . If resistance between all pairs of wires was 5 ohms or more, go to next step

  34. Using a DVOM, check resistance between the following circuits at IAC motor connector. Record resistance readings.
    • IAC motor connector driver No. 3 (Brown/White wire) and driver No. 4 (Violet/Black wire).

    If resistance between wires was less than 5 ohms, repair those wires for shorting together. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  . If resistance between wires was 5 ohms or more, go to next step.

  35. If no other potential causes are remaining, IAC motor is assumed to be defective. Replace IAC motor. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  36. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 4 between IAC motor connector (Violet/Black wire) and PCM connector C2 terminal No. 58 (Violet/Black wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 4. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  37. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  38. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  39. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 3 (Brown/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  40. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 3 between IAC motor connector (Brown/White wire) and PCM connector C2 terminal No. 48 (Brown/White wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 3. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  41. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  42. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  43. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 1 (Gray/Red wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 1 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  44. Using a DVOM, check resistance between IAC motor connector driver circuit No. 2 (Yellow/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  45. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 2 between IAC motor connector (Yellow/Black wire) and PCM connector C2 terminal No. 49 (Yellow/Black wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 2. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  46. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  47. Using a DVOM, check resistance between IAC motor connector driver circuit No. 3 (Brown/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  48. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  49. Turn ignition off. Using a DVOM, check resistance between IAC motor connector driver circuit No. 4 (Violet/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 4 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  50. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of IAC driver circuit No. 1 between IAC motor connector (Gray/Red wire) and PCM connector C2 terminal No. 57 (Gray/Red wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAC driver circuit No. 1. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  51. Inspect PCM connector C2 and wiring for corroded, damaged, pushed out or miswired terminals. If connector and wiring are okay, go to next step. If connector and wiring are not okay, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  52. Using a DVOM, check resistance between IAC motor connector driver circuit No. 1 (Gray/Red wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 1 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  53. Using a DVOM, check resistance between IAC motor connector driver circuit No. 2 (Yellow/Black wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 2 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  54. Using a DVOM, check resistance between IAC motor connector driver circuit No. 3 (Brown/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair IAC driver circuit No. 3 short to ground. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
  55. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A: ROAD TEST FOR OBD II VERIFICATION  .
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