Component Location
Description
1. General Description
The Idle Speed Control Actuator (ISCA) is installed on the intake manifold and controls the intake airflow that is by-passed 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.
2. DTC Description
The ECM sets DTC P1505 if the ECM detects that the ISCA (OPEN) control line is open or short to ground.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
Monitoring Strategy | ? 1. Signal check Low ? 2. Signal interruption ? 3. Rationality check | ? Open circuit in power line. ? Open circuit in control line. ? Short circuit in control line. ? Bad ISCA. ? Bad ECM. |
Threshold value | 1 | ? Short circuit to GND / Air passage : 100% |
2 | ? Wire disconnection / Air passage : 0% |
3 | |
Fail safe astion | 1 | ? Action power stage(clising) : ON ? Air passage : 50% |
2 | ? Action power stage(clising) : OFF ? Air passage : Limp home |
3 | |
Diagnostic Time | |
MIL on condition | |
Specification
Service standard |
A/CON switch OFF : 25~45% |
A/CON switch ON : 35~55% |
Waveform Inspection in Oscilloscope Mode
Start engine and warm up to operating temperature.
Probe(+) : ISCA harness connector NO3.
Probe(-) : Chassis ground.
Specification
Service standard |
A/CON switch OFF : 25~45% |
A/CON switch ON : 35~55% |
Schematic Diagram
Signal Waveform
Using the channel 1,2 of scan tool,it is the waveform at terminal 1,3 of ISCA in idling
The wave must be opposite to each other.
The lower voltage must be below 1V and the upper must be battery voltage.
Is Signal Switching Properly?
If the waveform changes as TPS changes or as A/CON switch on and off,it is normal.
In case there is no symptom and wrong data but DTC is shown |
The problem may be intermittent so slightly shake the connector and harness vertically and horizontally to check if there is any data changes |
If the data changes normally, the problem was intermittent so erase DTC and verify the same DTC reoccure. Go to "Terminal and Connector inspection" procedure. |
In case there is symptom and wrong data with DTC |
Check open,short or connector’s connection for ISCA. |
Check the deterioration of ISCA performance. Go to "Signal circuit inspection" procedure. |
Signal Waveform
Using the channel 1,2 of scan tool,it is the waveform at terminal 1,3 of ISCA in idling
The wave must be opposite to each other.
The lower voltage must be below 1V and the upper must be battery voltage.