DTC P1517: ISC Solenoid Valve Signal #4 Circuit Malfunction (High Input)

OUTLINE OF DIAGNOSIS
- Detect the open/short circuit of idle air control solenoid valve.
- Judge NG when the output terminal is High level even though ECM outputs ON signal.
COMPONENT DESCRIPTION

Fig 1: ISC Solenoid Valve Signal #4 Circuit Malfunction (High Input)
Courtesy of SUBARU OF AMERICA, INC.

ENABLE CONDITION

Secondary Parameters	Enable Conditions
Starter switch	OFF
Battery voltage	> 10.9 V

GENERAL DRIVING CYCLE
Perform the diagnosis continuously when starter switch is OFF.

DIAGNOSTIC METHOD

Abnormality Judgment

Judge NG when the cumulative time until completing the malfunction criteria below becomes more than time needed for diagnosis.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Terminal voltage level when ECM outputs ON signal	High level

Time Needed for diagnosis: 0.5 seconds

Malfunction Indicator Light Illumination: Illuminates as soon as malfunction occurs.

Normality Judgment

Judge OK and clear the NG when the malfunction criteria below are completed.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Terminal voltage level when ECM outputs ON signal	Low level

DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" was performed
MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle was completed 3 times in a row
- When "Clear Memory" was performed
FAIL SAFE
- Cut the fuel of all cylinders, #1 cylinder or #1, #2 cylinder according to throttle position, engine speed, vehicle speed.
- ISC closed loop compensation value becomes zero. [ISCCL = 0 (1/min)]
ECM OPERATION AT DTC
Memorize the freeze frame data. (For test mode $02)