The ISCA (Idle Speed Control Actuator) is designed to maintain a steady desired idle speed. Idle airflow is adjusted through the idle air actuator in order to maintain the desired idle speed under various load conditions. Load conditions vary due to numerous factors, such as engine temperature, air conditioning, electrical load and power steering load.
If there is Open or Short to ground in ISCA circuit, ECM sets DTC P0508.
Item
Detecting Condition
Possible Cause
DTC Strategy
Rationality check, low
Poor connection
Open or short to ground in control circuit
ISCA
Enable Conditions
Vehicle speed = 0
Coolant temperature > 80?
Intake air temperature > 15?
Idle status
No error on the related sensors. (PCSV, VSS, ECTS, IATS, etc)
Threshold Value
Shorted to ground or disconnected
Diagnostic Time
Continuous
MIL ON Condition
3 driving cycle
Specification
Opening Coil Resistance (O)
11.1 ~ 12.7 [20 ? 68 ?]
Closing Coil Resistance (O)
14.6 ~ 16.2 [20 ? 68 ?]
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.