Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Chevrolet >> 1999 >> Tracker 4D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0505: Idle Control System >> Diagnosis & Repair

Diagnosis & Repair

  1. If OBD system check has been performed, go to next step. If OBD system check has not been performed, go to ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on, with engine off. Using scan tool, perform clear information function. Operate vehicle within freeze frame conditions. Retrieve codes. If DTC P0505 is set, go to next step. If DTC P0505 is not set, go to DIAGNOSTIC AIDS .
  3. Turn ignition off. Disconnect IAC valve harness connector. Using a test light connected to ground, probe IAC valve ignition positive voltage circuit at IAC valve harness connector. See ENGINE PERFORMANCE WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  7.
  4. Using DVOM, measure resistance between the following terminals on IAC valve: terminals No. 1 and 2, terminals No. 2 and 3, terminals No. 4 and 5, and terminals No. 5 and 6. See ENGINE PERFORMANCE WIRING DIAGRAMS article. If resistance is 35-43 ohms at 68°F (20°C) at all terminals, go to next step. If resistance is not 35-43 ohms at 68°F (20°C) at all terminals, go to step  8.
  5. Disconnect air intake hose from top of IAC valve. Blow air into air intake port of IAC valve. Air should not pass through IAC valve. Apply battery voltage to terminal No. 2 (ignition positive voltage circuit) at IAC valve (valve side). Ground terminal No. 1 (control circuit) at IAC valve (valve side). Blow air into air intake port of IAC valve. Air should now pass through IAC valve. If IAC valve operates as described, go to next step. If IAC valve does not operate as described, go to step  8.
  6. Check for an open or short IAC valve control circuit between IAC valve and PCM. Repair as necessary. After repairs, go to step  10. If circuit is okay, go to step  9.
  7. Check for an open or short IAC valve ignition positive voltage circuit between main relay and IAC valve. Repair as necessary. After repairs, go to step  10.
  8. Replace IAC valve. After repairs, go to step  10.
  9. Replace PCM. Program PCM using required equipment. After replacing PCM, go to next step.
  10. After repairs, using scan tool, clear DTC information. Road test vehicle within freeze frame conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
scientia non olet · About Mike's Workshop Manuals