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DTC P0505: Idle Air Control Motor Circuits: Testing

  1. 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 INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn the ignition off. Disconnect the IAC Motor harness connector. Disconnect the PCM harness connectors. The following steps are checking for a short between the IAC Driver circuit. Measure the resistance between the (K59) IAC #1 Driver circuit and #2, #3, #4 Driver circuits at the IAC Motor harness connector. Is the resistance below 100 ohms on any of the Drivers? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
    3. NOTE: The following steps are checking for a short between the IAC Driver circuits.
  3. Measure the resistance between the (K40) IAC #2 Driver circuit and #3, #4 Driver circuits at the IAC Motor harness connector. Is the resistance below 100 ohms on any of the Drivers? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
    4. NOTE: The following steps are checking for a short between the Driver circuits.
  4. Measure the resistance between the (K60) IAC #3 Driver circuit and the (K39) IAC #4 Driver circuit at the IAC Motor harness connector. Is the resistance below 100 ohms? If yes, repair the IAC Driver Circuits that are shorted together. If no, go to next step.
  5. 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.
    NOTE: Remove the jumper wire and install the ASD Relay before continuing.
  6. Turn the ignition off. 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 100 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.
  7. Turn the ignition off. Reconnect PCM harness connectors. Start and idle the engine. Using a test light connected to ground, probe the IAC Driver #1 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 .
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