P0505

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 bypasses 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
The IAC valve-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.




CONSULT-II Reference Value in Data Monitor Mode




ECM Terminals and Reference Value
Specification data are reference values and are measured between each terminal and 32 (ECM ground).

On Board Diagnosis Logic:

DTC Confirmation Procedure

NOTE:
- If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch OFF and wait at least 5 seconds before conducting the next test.
- Perform "Procedure for malfunction A" first. If DTC cannot be confirmed, perform "Procedure for malfunction B".

PROCEDURE FOR MALFUNCTION A

TESTING CONDITION: Before performing the following procedure, confirm battery voltage is more than 10.5 V with ignition switch ON.

With CONSULT-II
1. Turn ignition switch ON.
2. Select "DATA MONITOR" mode with CONSULT-II.




3. Start engine and run it at idle at least 2 seconds.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
Follow the procedure "With CONSULT-II".

PROCEDURE FOR MALFUNCTION B

TESTING CONDITION:
- Before performing the following procedure, make sure battery voltage is more than 11 V at idle.
- Always perform at a temperature above -10 °C (14 °F).

With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 5 seconds.
3. Turn ignition switch ON again and select "DATA MONITOR" mode with CONSULT-II.




4. Start engine and run it for at least 6 minute at idle speed.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
Follow the procedure "With CONSULT-II".

EC-AAC/V-01:

Wiring Diagram

Diagnostic Procedure

Step 1 - 2:

Step 3 - 5: