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ISC - where to buy, how to check wiring harness.

Posted by alIan, Jun 8, 2006

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  1. Anthony Boni

    Anthony Boni Proven Member

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    Yeah that’s what I’ve been told as well, however the manual is telling me otherwise. Unless I’m reading something wrong. The harness looks unmolested. I pulled off some of the wire loom to expose approximately 9” of the ISC harness.
     

    Attached Files:

    Last edited: Aug 24, 2018
  2. chrysler kid

    chrysler kid Proven Member

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    Alright.

    With your spare isc in the throttle body use your good isc and have some one start the car. The goal here is to watch the car set the full range of motions for the isc.

    The isc if I recall correctly will go full in to start the vehicle and then come back out after a few seconds. You would then ideally have the person in the car trigger position 30 which is full closed using dsmlink.

    Basically to avoid that you would be probing the pins on the harness to observe voltage going into the isc. The factory manual calls for the special wire harness tester harness but it's a waste of time, you can observe your own idle air control valve function

    Again the codes triggered for idle air control valve are specifically regarding car going into closed loop at full operating temperature and the idle being 750+/-100 rpms. Once the idle air control valve is fully closed at position 30 you would adjust the base idle set screw ontop of the throttle body to the desired rpm.

    On 2g cars there is a blue pigtail on the firewall next to the ignition coil resistor box you can jump with a paper clip to set the idle air control valve to full shut (position 30) to set your base idle with the base idle set screw
     

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  3. Anthony Boni

    Anthony Boni Proven Member

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    Hey thanks for the advice. I have a few questions though: How do you have someone else trigger position 30? I know ideally you want your ISC at 30 steps +/- 5. But what do you mean by have someone else trigger position 30?

    Also, how do I probe my harness with my ISC plugged in? What am I actually probing? The two red wires from the MPI relay? Sorry electricity and I do not get along. Thanks!
     
  4. chrysler kid

    chrysler kid Proven Member

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    To trigger position 30 you would need to have dsmlink ECU in your car and have a laptop running the ecmtuning software.

    The back probing procedure can be found in the factory service manual. I don't have the manual infront of me but the eci sends 5 volts to each coil in the isc to trigger movement of the isc motor.
     

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  5. Anthony Boni

    Anthony Boni Proven Member

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    I have V3 full Are you talking about grounding the ground and diagnostic pin? When I did do that it put my ISC at 9 steps and stayed there.

    I just finished testing all of the wires for continuity and measured resistance. Each wire has .6 ohms and None of the 4 wires have shorted to one another. I have to test voltage now, but I do not know how to do that.
     
    Last edited: Aug 24, 2018
  6. chrysler kid

    chrysler kid Proven Member

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    fwd · automatic · 2G DSM

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    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM

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    14.1 @ 97 · 2G DSM
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  7. Anthony Boni

    Anthony Boni Proven Member

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    Alright thanks for the heads up.


    So I’ve tested my ISCs; 4 of them now. Three of the 4 have a resistance of 41 ohms because they are the newer black top motors. The brown one I have has a resistance of 31 ohms. During the 6 volt test, only one of my motors twitched.

    I tested the 4 wires (blue, yellow, white, and black) for continuity and shorts and they were all fine. I just did what it told me to do in the link you referenced me to and tested the harness’ two power wires from the MPI relay. I have 12.6 volts coming from both of them. The screenshot that he posted says one should receive less voltage. But I was receiving 12.6 in both.

    My ECU is good, my harness seems to be good, and I have a good ISC motor.
     
  8. PlanZero

    PlanZero Proven Member

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