Code No. P0505: Idle Speed Control (ISC) System

FUNCTION

The amount of air taken in during idling is regulated by the opening and closing of the throttle valve.
The engine-ECU <M/T> or engine-A/T-ECU <A/T> checks the difference between the actual engine speed and the target engine speed.

TROUBLE JUDGMENT

Check Conditions

The vehicle speed has reached 1.5 km/h or more at least once.
During the closed-loop idle speed control.

Judgment Criterion

The actual idle speed is higher than the target idle speed by 300 r/min or more for 10 seconds.

Check Conditions

The vehicle speed has reached 1.5 km/h or more at least once.
During the closed-loop idle speed control.
The highest ambient temperature at the last drive is 45°C or less.
The engine coolant temperature is approx. 77°C or higher.
The battery voltage is 10 V or more.
The intake air temperature is -10°C or higher.

Judgment Criterion

The actual idle speed is higher than the target idle speed by 200 r/min or more for 10 seconds.

Check Conditions

During the closed-loop idle speed control
The engine coolant temperature is approx. 77°C or higher.
The battery voltage is 10 V or more.
The power steering switch is in OFF position.
The charging efficiency is 40 % or less.
The intake air temperature is -10°C or higher.

Judgment Criterion

The actual idle speed is lower than the target idle speed by 100 r/min or more for 10 seconds.

PROBABLE CAUSE

Throttle valve area is dirty.
Intake system vacuum leak.
Failed engine-ECU <M/T>
Failed engine-A/T-ECU <A/T>

STEP 1: M.U.T.-III diagnosis code

Q. Diagnosis code set?

	Inspection chart for diagnosis code (Refer to .)

	Go to Step 2 .

STEP 2: Check throttle body (throttle valve portion) for contamination.

Q. Is the check result normal?

	Go to Step 3 .

	Clean throttle body (throttle valve portion) (Refer to ).

STEP 3. Check air intake from intake hose and inlet manifold.

Q. Is the check result normal?

	Go to Step 4 .

	Repair.

STEP 4. Check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).