DTC P0505: Idle Air Control Motor Circuits: Testing
- Turn ignition on, engine not running. With the DRBIII®, read DTCs. Is the Good Trip counter displayed and equal to zero? If yes, go to next step. If no, go to step 8.
- Turn the ignition off. Disconnect the IAC Motor harness connector. Disconnect the PCM harness connectors. Measure the resistance between the IAC #1 Driver circuit and #2, #3, #4 Driver circuits at the IAC Motor harness connector. Is the resistance below 5.0 ohms on any of the Drivers? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
- Measure the resistance between the IAC #2 Driver circuit and #3, #4 Driver circuits at the IAC Motor harness connector. Is the resistance below 5.0 ohms on any of the Drivers? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
- Measure the resistance between the IAC #3 Driver circuit and the #4 Driver circuit at the IAC Motor harness connector. Is the resistance below 5.0 ohms? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
- Remove the ASD Relay from the PDC. Using a jumper wire, jumper between the Fused B+ circuit and ASD Relay Output circuit in the PDC. Turn ignition on, engine not running. Measure the voltage of each of the IAC Driver circuit. Is the voltage above 1.0 volt at any IAC Driver circuit? If yes, repair the IAC Driver circuit(s) for a short to voltage. If no, go to next step.
- Measure the resistance between ground and each IAC Driver circuit at the IAC Motor harness connector. Repeat each measurement for each IAC Driver circuit. Is the resistance below 5.0 ohms at any IAC Driver circuit? If yes, repair the IAC Driver circuit(s) for a short to ground. If no, go to next step.
- Ensure ignition is off. Reconnect PCM connectors. Install ASD Relay. Ensure IAC Motor is disconnected. Start and idle the engine. Using a test light connected to ground, probe the IAC #1 Driver circuit for 10 seconds. Repeat test for the remaining IAC Motor Driver circuits. Does the test light turn on and off while probing each IAC Motor Driver circuit? If yes, replace the Idle Air Control Motor. If no, replace PCM. Program the new PCM. See PROGRAMMING .
- The conditions that set the DTC are not present at this time. The following may help in identifying the intermittent condition. With the engine running at normal operating temperature, monitor the DRBIII® parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set. Review the DRBIII® Freeze Frame information. If possible, try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals. Were any of the above conditions present? If yes, repair as necessary. If no, test is complete.
WARNING:
When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.