Idle Air Control System
SYSTEM INSPECTION1. Start the engine and run it at idle.
2. Disconnect the IAC valve connector and verify that the engine rotation becomes rough or the engine stalls.
3. If the engine condition will not change, do as follows.
A Connect the New Generation Star (NGS) tester.
B Verify that diagnostic trouble code No. P0505 is not displayed. If code No. P0505 is shown, carry out troubleshooting of the code No. P0505.
C Select the SIMULATION TEST function on the NGS display.
D Change the duty value of the IAC valve to 50% by using the "IACV" and verify that the idle speed increases.
I. If the idle speed increases, replace the ECM.
II. If the idle speed does not change, replace the BAC valve
4. Warm up the engine to normal operating temperature and run it at idle.
5. Turn the electrical loads on and verify that the engine speed is within the specification.
6. If not as specified, check the related switches and wiring harnesses.