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DTC P1504: IAC Valve Circuit Malfunction: Testing

NOTE: Ensure freeze frame data has been recorded. Check for service bulletins and on-line information.
  1. Using scan tool, clear DTC. Start engine. Warm engine to operating temperature. If DTC P1504 is present, go to next step. If DTC P1504 is not present, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
  2. Turn ignition off. Disconnect IAC valve harness connector. Check IAC valve and harness connector terminals. If no problem is found, go to next step. If any problem is found, repair as necessary. After repair, go to step  12 .
  3. Check resistance between IAC valve component terminals. If resistance is 8.69-10.56 ohms, go to next step. If resistance is not 8.69-10.56 ohms, replace IAC valve. After repair, go to step  12 .
  4. Turn ignition on. Check voltage between IAC valve harness connector terminal No. 1 (Green/Yellow wire) and ground. If battery voltage is not present, problem is on power circuit. Go to next step. If battery voltage is present, problem is on control circuit. Go to step  8 .
  5. Turn ignition off. Disconnect PCM connector. PCM is mounted to passenger floor, behind glove box. Check PCM and harness connector terminals. If no problem is found, go to next step. If any problem is found, repair as necessary. After repair, go to step  12 .
  6. Turn ignition off. Check for continuity between IAC harness connector terminal No. 1 (Green/Yellow wire) and ground. If continuity is not present, go to next step. If continuity is present, repair short to ground in Green/Yellow wire. After repair, go to step  12 .
  7. Turn ignition off. Disconnect PCM harness connector. Connect breakout box to PCM connector. Leave PCM disconnected. Check continuity between IAC harness connector terminal No. 1 and breakout box terminal No. 54. If continuity is present, go to step  12 . If continuity is not present, repair Green/Yellow wire. After repair, go to step  12 .
  8. Turn ignition off. Disconnect PCM connector. Check PCM and harness connector terminals. If no problem is found, go to next step. If any problem is found, repair as necessary. After repair, go to step  12 .
  9. Turn ignition on. Check voltage between IAC valve harness connector terminal No. 2 (Black/Yellow wire) and ground. If battery voltage is not present, go to next step. If battery voltage is present, repair short to power on Black/Yellow wire. After repair, go to step  12 .
  10. Turn ignition off. Check continuity between IAC valve harness connector terminal No. 2 (Black/Yellow wire) and ground. If continuity is not present, go to next step. If continuity is present, repair short to ground on Black/Yellow wire. After repair, go to step  12 .
  11. Disconnect PCM harness connector. Connect breakout box to PCM connector. Leave PCM disconnected. Check continuity between IAC harness connector terminal No. 2 and breakout box terminal No. 83. If continuity is present, go to next step. If continuity is not present, repair Black/Yellow wire. After repair, go to next step.
  12. Reconnect all components. Using scan tool, clear all DTCs. Start engine. Warm engine to operating temperature. Recheck DTCs. If same DTC is present, replace PCM and go to next step. If same DTC is not present, go to next step.
  13. Perform after repair procedure. See AFTER REPAIR PROCEDURE  . If no DTC is present, testing is complete. If any DTC is present, go to appropriate test for diagnosis and repair.
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