Idle Speed/Throttle Actuator - Electronic: Testing and Inspection

IDLE SPEED CONTROL (ISC) ACTUATOR
The intake air volume at idle is controlled by opening or closing the motor valve provided in the air path that bypasses the throttle valve.

NOTE:
1. If the stepper motor step increases to 100-120 steps or decreases to 0 steps, check for faulty stepper motor or open circuit in the harness.
2. If the idle speed control motor is normal but the stepper motor steps are out of specification, check the following:
- Poorly adjusted reference idle speed
- Deposit on the throttle valve
- Air leaking into the intake manifold through gasket gap
- Loose EGR valve seat
- Poor combustion in the cylinder (faulty ignition plug, ignition coil , injector, low compression pressure, etc.)




Using GST

NOTE: When the vehicle is new (about 500 km [at 20°C (68°F)300 miles]), the stepper motor steps may be about 30 steps more than standard.










HARNESS INSPECTION PROCEDURES







Actuator Inspection

Operation Sound Check
1. Check for the sound of the stepper motor after the ignition is switch ON (but without starting the motor).
2. If the operation sound cannot be heard, check the stepper motor's circuit.
3. If the circuit is normal, the problem may be the stepper motor or the ECM
Resistance Measurement between terminals Measure the resistance between the respective terminals
Standard value
Terminals 2-3 or 1 28-33 Ohms @ 20°C (68°F)
Terminals 5-4 or 6 28-33 Ohms @ 20°C (68°F)

Operation Check
Apply voltage as follows and check whether or not stepper motor movement occurs.
1. Connect the power supply (approx. 6V) terminal (+) to terminals 2 and 5 of the connector.
2. Connect the power supply (-) terminal to terminals 3 and 4
3. Connect the power supply (-) terminal to terminals 3 and 4
4. Connect the power supply (-) terminal to terminals 3 and 6
5. Connect the power supply (-) terminal to terminals 1 and 6
6. Connect the power supply (-) terminal to terminals 1 and 4.
- Repeat the tests in sequence from (6) to (1) if vibration is detected, the stepper motor can be considered to be normal