P0505

P0505 ISC SYSTEM

Description




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 and power steering).

COMPONENT DESCRIPTION




IACV-AAC 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.

Consult-II Reference Value In Data Monitor:

ECM Terminals And Reference Value:

On Board Diagnosis Logic
Malfunction is detected when (Malfunction A) the IACV-AAC valve does not operate properly, (Malfunction B) the IACV-AAC valve does not operate properly.

POSSIBLE CAUSE
- Harness or connectors
(The IACV-AAC valve circuit is open.)

- Harness or connectors
(The IACV-AAC valve circuit is shorted.)

- IACV-AAC valve

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 1st trip DTC cannot be confirmed, perform "PROCEDURE FOR MALFUNCTION B".

PROCEDURE FOR MALFUNCTION A

TESTING CONDITION:
Before performing the following procedure, confirm that 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. Wait 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, confirm that battery voltage is more than 11 V at idle.

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 1 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 - 3:

Step 4 - 6: