M/T

DTC P0505 IDLE AIR CONTROL SYSTEM (M/T)

CIRCUIT DESCRIPTION

DTC Detection Condition:

The rotary solenoid type Idle Air Control (IAC) valve is located under the throttle body, and intake air that is bypassing the throttle valve flows into the IAC valve through the passage. In this way, the intake air volume bypassing the throttle valve is regulated controls the engine speed.

The ECM operates the IAC valve only to perform idle-up and provide feedback for the target idling speed.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Condition:

Typical Malfunction Thresholds:

The idle speeds are determined depending on the volume of air that passes through the IAC valve. When the volume is large, the idle speed is higher. When the volume is small, the idle speed is lower. The IAC valve controls the volume of air that by-passes the throttle valve. The ECM sends duty signals to the IAC valve and drives the IAC valve stepper motor to determine the volume of air that by-passes the throttle valve. Although the vehicle is stopped several times and the ECM feedback control of the idle engine rpm is activated, the actual idle rpm does not reach the targeted rpm and the learned value angle of the idle air control (IAC) remains at the maximum or remains at the minimum. The ECM would then determine that the IAC system has a malfunction.

Example:
For a stopped vehicle with an idling engine, DTC P0505 will be set if the engine's targeted rpm and actual rpm exceeds 200 rpm on 5 different occasions.

HINT: *: Threshold rpm is varied by an engine load.

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- The throttle position may be slightly open (accelerator pedal slightly depressed) as a result of an object such as the floor carpet. In such cases, DTC P0505 may be detected.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.

Step 1 - 3:

Step 4 - 6:

Step 7 - 9:

Hand-held tester

Step 1 - 4:

Step 5 - 7:

OBD II scan tool (excluding hand-held tester)

CHECK FOR INTERMITTENT PROBLEMS

Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.

a. Clear the DTCs.
b. Change to check mode.
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.