The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support Rix Racing

1G New ISC

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


10+ Year Contributor
Oct 19, 2008
Newberg, Oregon
92 tsi. Picked up a new ISC one of the black plastic ones. Check the resistance first and it is around 40.9 between the pin 1-2 2-3 4-5 5-6. Plugged it into the the harness and turned the key to on and I don’t get any in and out movement or rotational movement, and a very quiet vibration sound similar to the bad one but almost inaudible, You can barley hear it in the video. Did I get a bad ISC from the parts store perhaps?

You must be logged in to view this image or video.


10+ Year Contributor
Oct 19, 2008
Newberg, Oregon
Well I put the new one in form the video that I was skeptical about and it wants to cold start idle at 3500. Hoping that it is faulty and causing this. I double checked my tps and it is at .49v. New gaskets on both sides of the throttle body, ic clamp tight, vacuum line hooked back up exactly as the pic I took. Tps and new isc hooked up. Any advice?

Edit. Hooked up my old isc and it fired up fine. It idles around 2500 when it’s cold and settles to about 1100 which is probably a little high. I’ll be getting my service manuals soon which will help a lot with get stuff figured out. Any feed back about the new ISC would be awesome or if I should be chasing a different issue now

Also unplugged the old ISC while the car was idling and got zero change in rpm or sound of it idling
Last edited:

Vegas Smith

20+ Year Contributor
Dec 2, 2002
Houston, Texas
It's hard to tell from the pics but you want look for any bubbling on the sides of the drivers. Can't tell from the top. The idle system is very particular and setting the idle will depend on whether you have ecmlink or not. 100%, any time you want to adjust your isc you need to warm the car up to full operating temp then turn it off the engine while leaving the power on. Unplug the isc and turn the ignition/power off. Plug in the isc and now restart the car. You'll hear the isc reset itself and will now be ready to be adjusted starting from scratch. The car will be warm and ready for any idle adjustments.



15+ Year Contributor
Mar 11, 2004
Longmont, Colorado
The ISC won't generally move unless the car is running and it's actively trying to adjust idle. That being said, if you reset the ecu by disconnecting the battery terminal, on first power up the ecu will go into a "rehoming" mode for the ISC and you should hear and see it move provided everything is working as it should.
I would recommend pulling the battery terminal and then reconnect it and have someone turn the key to ON while you watch the ISC.


DSM Wiseman
Feb 3, 2002
St Charles, Illinois
Since the prior ISC at least buzzed I would expect this one do at least that but I didn't see any motion in your video.

While it's easy to see the worst cases of damage to the ISC drivers it's impossible without metering to see if the ECU pins back to the drivers the circuit traces are good and without a special load tested to know if the driver is damaged but not burnt up. For example one of the ISC traces passes in a via under the front capacitor. Any leakage there will usually open that trace.

A significant percentage of the ECUs I saw on my bench had ISC drivers that couldn't pull one of more ISC coils low enough to make it step consistently. They looked perfect but in use it was clear they were damaged.
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Latest Classifieds