DTC P0505: IAC MOTOR CIRCUIT Dodge Ram Wagon B1500

Note. For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see RAM VAN & RAM WAGON wiring diagram in WIRING DIAGRAMS article.

Note. DTC P0505: IAC MOTOR CIRCUIT is monitored immediately after ignition is turned on with battery voltage more than 11.5 volts. DTC may be stored in Powertrain Control Module (PCM) when PCM senses a short to ground or battery voltage on any of 4 IAC driver circuits for 100 milliseconds while IAC motor is active. Possible causes are: DTC does not match freeze frame DTC, defective IAC motor, defective PCM, defective connector or defective wiring.

1. Turn ignition on, with engine off. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP COUNTER is displayed and displayed count is "0", go to step 4). If DTC SPECIFIC GOOD TRIP COUNTER is not displayed or displayed count is not "0", go to next step.
2. Determine if DTC matches FREEZE FRAME DTC. If DTC is equal to FREEZE FRAME DTC, go to next step. If DTC is not equal to FREEZE FRAME DTC, repair DTC using FREEZE FRAME data.
3. Road test vehicle under conditions in FREEZE FRAME data. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP COUNTER displayed count changes to "0", go to next step. If DTC SPECIFIC GOOD TRIP COUNTER displayed count does not change to "0", go to step 26).
4. Start engine and allow it to idle. Disconnect IAC motor connector. IAC motor is located on throttle body. Clean and/or repair connector as necessary. Using a voltmeter, check voltage on IAC motor connector, driver No. 1 circuit (Gray/Red wire). If voltage goes to more than 5 volts at any time, go to next step. If voltage does not go to more than 5 volts at any time, go to step 24).
5. Turn ignition off. Ensure IAC motor connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Clean and/or repair connectors as necessary. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 4 circuit (Violet/Black wire). If resistance is less than 5 ohms, repair driver No. 4 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
6. Start engine and allow it to idle. Ensure IAC motor connector is still disconnected. Using a voltmeter, check voltage on IAC motor connector, driver No. 2 circuit (Yellow/Black wire). If voltage goes to more than 5 volts at any time, go to next step. If voltage does not go to more than 5 volts at any time, go to step 21).
7. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 1 circuit (Gray/Red wire). If resistance is less than 5 ohms, repair driver No. 1 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
8. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and IAC motor connector, driver No. 2 circuit (Yellow/Black wire). If resistance is less than 5 ohms, repair driver No. 2 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
9. Start engine and allow it to idle. Ensure IAC motor connector is still disconnected. Using a voltmeter, check voltage on IAC motor connector, driver No. 3 circuit (Brown/White wire). If voltage goes to more than 5 volts at any time, go to next step. If voltage does not go to more than 5 volts at any time, go to step 19).
10. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 3 circuit (Brown/White wire). If resistance is less than 5 ohms, repair driver No. 3 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
11. Start engine and allow it to idle. Ensure IAC motor connector is still disconnected. Using a voltmeter, check voltage on IAC motor connector, driver No. 4 circuit (Violet/Black wire). If voltage goes to more than 5 volts at any time, go to next step. If voltage does not go to more than 5 volts at any time, go to step 18).
12. Ensure engine is still idling. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. While monitoring IAC motor operation, wiggle wiring harness from IAC motor to PCM. If idle speed increases and decreases, go to next step. If idle speed does not increase and decrease, go to step 17).
13. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between IAC motor connector, driver No. 1 circuit (Gray/Red wire) and each remaining driver circuit. If resistance is less than 5 ohms between any 2 circuits, repair driver circuits that are shorted together. Perform TEST VER-5A. If resistance is 5 ohms or more between all driver circuits, go to next step.
14. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance between IAC motor connector, driver No. 2 circuit (Yellow/Black wire) and each remaining driver circuit. If resistance is less than 5 ohms between any 2 circuits, repair driver circuits that are shorted together. Perform TEST VER-5A. If resistance is 5 ohms or more between all driver circuits, go to next step.
15. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance between IAC motor connector, driver No. 3 circuit (Brown/White wire) and driver circuit No. 4 (Violet/Black wire). If resistance is less than 5 ohms, repair driver No. 3 circuit for short to driver No. 4 circuit. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
16. Start engine and allow it to idle. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. While monitoring IAC motor operation, wiggle wiring harness from IAC motor to PCM. If IAC motor stops operating at any time while wiggling wiring harness, repair wiring harness where wiggling caused IAC motor to stop operating. Perform TEST VER-5A. If IAC motor does not stop operating at any time while wiggling wiring harness, go to next step.
17. At this time, IAC motor is assumed to be defective. Replace IAC motor. Perform TEST VER-5A.
18. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance of IAC motor connector, driver No. 4 circuit (Violet/Black wire). If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A. If resistance is 5 ohms or more, repair open driver No. 4 circuit. Perform TEST VER-5A.
19. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 3 circuit (Brown/White wire). If resistance is less than 5 ohms, repair driver No. 3 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
20. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance of IAC motor connector, driver No. 3 circuit (Brown/White wire). If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A. If resistance is 5 ohms or more, repair open driver No. 3 circuit. Perform TEST VER-5A.
21. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 1 circuit (Gray/Red wire). If resistance is less than 5 ohms, repair driver No. 1 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
22. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and IAC motor connector, driver No. 2 circuit (Yellow/Black wire). If resistance is less than 5 ohms, repair driver No. 2 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
23. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance of IAC motor connector, driver No. 2 circuit (Yellow/Black wire). If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A. If resistance is 5 ohms or more repair open driver No. 2 circuit. Perform TEST VER-5A.
24. Ensure ignition is off. Ensure IAC motor and PCM connectors are still disconnected. Using an ohmmeter, check resistance between ground and IAC motor connector, driver No. 4 circuit (Violet/Black wire). If resistance is less than 5 ohms, repair driver No. 4 circuit for short to ground. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
25. Turn ignition off. Ensure IAC motor and PCM connectors are still disconnected. Using ohmmeter, check resistance of IAC motor connector, driver No. 1 circuit (Gray/Red wire). If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A. If resistance is 5 ohms or more, repair open driver No. 1 circuit. Perform TEST VER-5A.
26. Start engine and allow it to idle. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. While monitoring IAC motor operation, wiggle wiring harness from IAC motor to PCM. If IAC motor stops operating at any time while wiggling wiring harness, repair wiring harness where wiggling caused IAC motor to stop operating. Perform TEST VER-5A. If IAC motor does not stop operating at any time while wiggling wiring harness, test is complete.