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Home >> Isuzu >> 2000 >> Rodeo LSE, 2.2 D >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.2L >> Diagnostic Trouble Code Identification >> DTC P0506: IAC System Rpm Low >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic II (OBD-II) system check. See SELF-DIAGNOSTICS - INTRODUCTION article. Go to next step.
  2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
  3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, see DIAGNOSTIC AIDS . If ENGINE SPEED is not as specified, go to next step.
  4. Disconnect IAC harness connector. Install IAC Noid Light (J37027 or equivalent) in IAC harness connector. With engine running, monitor noid lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and back up to 1500 RPM. Both node lights should cycle Green and Red, but not OFF as RPM changes from 500 to 1500 RPM. If lights flash as specified, go to step  6. If lights do not flash as specified, go to next step.
  5. Check IAC "A" high and IAC "A" low, and IAC "B" high and IAC "B" low circuits for open or shorted condition. If such a condition is found, repair as necessary. Retest system. If no problem is found in high or low circuits, go to step  8.
  6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  7. Check for faulty connection at IAC harness connector. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
  8. Using a DVOM, check IAC valve solenoids for an open, short to ground or shorted together condition. If such condition exists, go to next step. If no problem is found with IAC valve solenoids, go to step  10.
  9. Replace IAC valve. Retest system.
  10. Replace and reprogram PCM using required equipment. See PROGRAMMING . Retest system.
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