Idle Speed/Throttle Actuator - Electronic: Testing and Inspection

SYSTEM DESCRIPTION
This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via IACV-AAC valve. The IACV-AAC valve repeats ON/OFF operation according to the signal sent from the ECM. The camshaft position sensor detects the actual engine speed and sends a signal to the ECM. The ECM then controls the ON/OFF time of the IACV-AAC valve so that engine speed coincides with the target value memorized in ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined by taking into consideration various engine conditions, such as during warm up, deceleration, and engine load (air conditioner, power steering and cooling fan operation).

COMPONENT DESCRIPTION




IACV-ACC valve
The IACV-AAC valve is moved by ON/OFF pulses from the ECM. The longer the ON pulse, the greater the amount of air that will flow through the valve. The more air that flows through the valve, the higher the idle speed.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
Procedure for malfunction A
WITH CONSULT
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT.
3. Start engine and run it at idle for at least 2 seconds.

OR

WITH GST
1. Start engine and run it at idle for at least 2 seconds.
2. Select "MODE 3" with GST.

OR

WITH NO TOOLS
1. Start engine and run it at idle for at least 2 seconds.
2. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.

Procedure for malfunction B
WITH CONSULT
1. Start engine and warm it up sufficiently.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON" again and select "DATA MONITOR" mode with CONSULT.
4. Start engine and run it for at least 30 seconds at idle speed.

OR

WITH GST
1. Start engine and warm it up sufficiently.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Start engine again and run it for at least 30 seconds at idle speed.
4. Select "MODE 3" with GST.

OR

WITH NO TOOLS
1. Start engine and warm it up sufficiently.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Start engine again and run it for at least 30 seconds at idle speed.
4. Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
5. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.




WIRING DIAGRAM




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION




Disconnect IACV-AAC valve harness connector.
- Check IACV-AAC valve resistance.

Resistance: Approximately 10 Ohms at 25°C (77°F)

- Check plunger for seizing or sticking.
- Check for broken spring.