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Home >> Chevrolet >> 1998 >> Venture Base, Van Cargo Extended >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0507 - Idle Control System High Rpm >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
  3. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, no problem is detected at this time. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, go to next step.
  4. Disconnect IAC valve harness connector. Install IAC Node Light (J 37027-A) to IAC valve harness connector. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring ENGINE SPEED display. If each node light cycles Red and Green but never off, go to step 6). If each node light does not cycle Red and Green, go to next step.
  5. Check for an open, short to voltage or short to ground in IAC valve related circuits between IAC valve and PCM. Repair as necessary. After repair is completed, go to step 11). If circuits are okay, go to step 9).
  6. Check for vacuum leaks. Check for binding throttle plate or throttle shaft. Check for misadjusted throttle and cruise control cables. Check PCV system operation. Repair as necessary. After repairs, go to step 11). If no problem is found, go to next step.
  7. Check for poor connection at IAC valve connector. Repair as necessary. After repairs, go to step 11). If no problem is found, go to next step.
  8. Replace IAC valve. Repair as necessary. After repairs, go to step 11). If no problem is found, go to next step.
  9. Check for poor connection at PCM valve connector. Repair as necessary. After repairs, go to step 11). If no problem is found, go to next step.
  10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  11. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, repair is complete. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, repeat step 2).
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