Idle Speed Control Motor Position Sensor

Operation

The idle speed control motor position sensor functions to convert the data concerning the position of the plunger (located within the idle- speed control motor) to Voltage, and to input that Voltage (as signals) to the engine control module. The engine control module, based upon those signals, then functions to regulate the idle-speed control motor.

The 5V power supply within the engine control module is supplied to the idle speed control position sensor; it then passes through the resistance within the sensor and is grounded at the engine control module

When the plunger located within the idle-speed control motor extends from its contracted condition, the resistance between the idle speed control motor position sensor's variable-resistance terminal and the ground terminal also increases in accordance with that extension. As a result, the Voltage of the idle speed control motor position sensor's variable-resistance terminal also becomes higher in accordance with the extension.

Troubleshooting Hints


Hint 1:

The idle speed control motor position sensor is the most important sensor for control of the idling speed; there is very often a malfunction of this sensor if a problem occurs when the engine load is caused to fluctuate, such as when, during idling, the air conditioning switch is switched back and forth between OFF and ON, etc.

Hint 2:

If the output Voltage of the idle speed control motor position sensor deviates from the standard value even though the results of the checking of the idle speed control motor position sensor harness and of the component itself are normal, the malfunction may be presumed to be among the following:

(1) Improper adjustment of the basic idling speed.
(2) Deposits adhering to the throttle valve.
(3) Air being taken into the intake manifold due to a gasket leak, etc.
(4) Improper seating of the EGR valve seat.
(5) Incomplete combustion within a cylinder. (Malfunction of spark plugs, ignition coil, injectors, compression pressure, etc.)





Inspection








Harness Inspection


Sensor Inspection

(1) Disconnect the idle speed control motor position sensor connector.






(2) Measure the resistance between terminals 2 and 3.

Standard value: 4-6 K Ohms.

(3) Disconnect the idle speed control motor connector.
(4) Connect DC 6V between terminals 1 and 2 of the idle speed control motor connector, and then measure the resistance between terminals 3 and 5 of the idle speed control motor position sensor connector when the idle speed control motor is activated (caused to expand and contract).

Standard value: Smooth increase/decrease in accordance with expansion and contraction of the idle speed control motor plunger.

Caution:Apply only a 6V DC or lower Voltage. Application of higher Voltage could cause locking of the servo gears.

(5) If there is a deviation from the standard value, or if the change is not smooth, replace the idle speed control motor assembly.