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 is to maintain idle speed according to various engine loads and conditions, and also to provide additional air during starting.
The ISCA consists of an opening coil, a closing coil, and a permanent magnet. Based on information from various sensors, the ECM controls both coils by grounding their control circuits. According to the control signals from the ECM, the valve rotor rotates to control the by pass airflow into the engine.
ECM sets DTC P1507 if the ECM detects that the ISCA (CLOSE) control line is open or short to ground.
Item
Detecting Condition
Possible Cause
DTC Strategy
Circuit continuity check, low (opening coil)
Contact resistance in connections
Open or short to ground in power circuit
Open or short to ground in control circuit
Faulty ISCA
Faulty ECM
Enable Conditions
-
Threshold Value
Short circuit to Ground
Wire disconnection
Diagnostic Time
MIL ON Condition
3 driving cycle
Temperature
ISCA COIL Resistance
20 ?
CLOSE COIL
16.6 ~ 18.6 ?
OPEN COIL
14.5 ~ 16.5 ?
The above waveforms are the voltage signals generated when ISCA operates. This ISCA type is duty type and thetime ratio opened determines duty amount. The left side is the waveform of ISCA Openingcoil during idle. The right side is the waveform of ISCA Closing coil during idle.