Troubleshooting

P0505 - Idle Control System Malfunction

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The rotary solenoid type IAC valve is located under the throttle body and intake air bypassing the throttle valve is directed to the IAC valve through the passage.
In this way the intake air volume bypassing the throttle valve is regulated, controlling the engine speed.
The ECM operates the IAC valve only to perform idle-up and provide feedback for the target idling speed.

Wiring Diagram:

Step 1 - 3:

Step 4 - 5:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the TOYOTA hand-held tester or OBDII scan tool, as freeze frame data records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

CHECK FOR INTERMITTENT PROBLEMS
TOYOTA hand-held tester only:
By putting the vehicle's ECM in the check mode, 1 trip detection logic is possible instead of 2 trip detection logic and the sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
1. Clear the DTC.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.