Federal

DIAGNOSTIC DETECTION LOGIC





CIRCUIT DIAGRAM





INSPECTION USING SCAN TOOL








HARNESS INSPECTION PROCEDURE

Using Oscilloscope
(1) Connect the probe to each oscilloscope pick-up point as shown in the circuit diagram.
(2) Start the engine.





(3) When the air conditioning switch is turned on, the idling speed increases to operate the idle speed control. Check the instantaneous waveform.

NOTE:
Keep in mind that the waveform can be observed only when idle speed control is in operation.

TROUBLESHOOTING HINTS
Hint 1:If the stepper motor step increases to 100 to 120 steps or decreases to 0 step, faulty stepper motor or open circuit in the harness is suspected.
Hint 2: If the idle air control motor harness and individual part checked good but the stepper motor steps are out of specification, the following faults are suspected.
(1) Poorly adjusted reference idle speed
(2) Deposit on the throttle valve
(3) Air leaking into the intake manifold through gasket gap
(4) Loose EGR valve seat
(5) Poor combustion in the cylinder (faulty ignition plug, ignition coil, injector, low compression pressure, etc.)

ACTUATOR INSPECTION
Checking the Operation Sound
(1) Check that the operation sound of the stepper motor can be heard after the ignition is switched ON (but without starting the motor).





(2) If the operation sound cannot be heard, check the stepper motor's activation circuit.
If the circuit is normal, it is probable that there is a malfunction of the stepper motor or of the engine control module.

Checking the Coil Resistance
(1) Disconnect the idle air control motor connector and connect the special tool (test harness).





(2) Measure the resistance between terminal (2) (white clip of the special tool) and either terminal (1) (red clip) or terminal (3) (blue clip) of the connector at the idle air control motor side.

Standard value: 28-33 Ohms at 2O°C (68°F)

(3) Measure the resistance between terminal (5) (green clip of the special tool) and either terminal (6) (yellow clip) or terminal (4) (black clip) of the connector at the idle air control motor side.

Standard value: 28-33 Ohms at 2O°C (68°F)

Operational Check
(1) Remove the throttle body.





(2) Remove the stepper motor.
(3) Connect the special tool (test harness) to the idle air control motor connector.





(4) Connect the positive (+) terminal of a power supply (approx. 6 V) to the white clip and the green clip.





(5) With the idle air control motor as shown in the illustration, connect the negative (-) terminal of the power supply to each clip as described in the following steps, and check whether or not a vibrating feeling (a feeling of very slight vibration of the stepper motor) is generated as a result of the activation of the stepper motor.
1) Connect the negative (-) terminal of the power supply to the red and black clip.
2) Connect the negative (-) terminal of the power supply to the blue and black clip.
3) Connect the negative (-) terminal of the power supply to the blue and yellow clip.
4) Connect the negative (-) terminal of the power supply to the red and yellow clip.
5) Connect the negative (-) terminal of the power supply to the red and black clip.
6) Repeat the tests in sequence from (5) to (1).
(6) If, as a result of these tests, vibration is detected, the stepper motor can be considered to be normal.