The Idle Speed Control Actuator(ISCA) is installed on the intake manifold and controls the intake airflow that is bypassed around the throttle plate to keep constant engine speed when the throttle valve is closed. The function of the ISCA valve is to maintain idle speed according to various engine loads and conditions, and also to provide additional air during starting. The ISCA valve consists of an opening coil, a closing coil, and a permanent magnet. Based on information from various sensors, the PCM controls both coils by grounding their control circuits. According to the control signals from the PCM, the valve rotor rotates to control the by pass airflow into the engine.
PCM sets DTC P1505 if the PCM detects that the ISCA(OPEN) control circuit is open or short to ground.
Item
Detecting Condition
Possible Cause
DTC Strategy
Electrical check
Open or short to ground in harness
Poor connection or damaged harness
Faulty ICA valve
Enable Conditions
10V < Battery voltage < 16V
Threshold Value
Short to ground or line break
Diagnostic Time
2 sec.
Mil On Condition
2 Driving Cycles
Temperature
Opening Coil(O)
Closing Coil(O)
20?(68?)
11.1~12.7
14.6~16.2
Fig.1) The above waveforms are the voltage signals generated when the ISCA operates. This ISCA is a duty type and the time opened determines the duty amount. The left side is the waveform of the ISCA Opening coil during idle.
The right side is the waveform of the ISCA Closing coil during idle.