Idle Speed Control (ISC) Motor Test

Idle Speed Control (ISC) Servo Circuit:

Use the following procedures to test the ISC Servo:

COMPONENT TEST
1. Disconnect the ISC servo connector.

Actuator Test:

2. Using an ohm meter, check the resistance between terminals 1 and 2.

Resistance
5 - 35 Ohms @68°F

3. Using a 6 VDC power supply, apply Voltage to terminals 1 and 2.

Results
The plunger should either extend or retract.

4. Using a 6 VDC power supply, apply Voltage to terminals 1 and 2, using opposite polarity than in step 3.


Results
The plunger should either extend or retract (opposite of the results from step 3).

CAUTION: Do not apply a Voltage higher than 6 Volts. If a higher Voltage is used, damage to the ISC servo can result.


HARNESS TEST
1. Disconnect the ECU and ISC connectors.
2. Using an ohm meter, check for continuity between ECU harness terminal 58 and ISC harness terminal 1.

Continuity
Should exist

3. Using an ohm meter, check for continuity between ECU harness terminal 59 and ISC harness terminal 2.

Continuity
Should exist

4. Using an ohm meter, check for continuity between ECU harness terminal 58 and ground.

Continuity
Should not exist

5. Using an ohm meter, check for continuity between ECU harness terminal 59 and ground.

Continuity
Should exist




If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, road test the vehicle to confirm that the repair has corrected the problem.
If the same problem reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.