ECM tune

[yukonbuck]

I just bought a 2002 duramax LB7 and it has a switch on the dash that has a wire running to the ECM. I assume that someone had the ECM programmed. When i flip the switch on it seems to cut power dramatically. Not sure which program someone had done or what it is supposed to do. Any help?? Thanks in advance,

Buck

[Buck]

Welcome to the forum! Lots of good reading here.

It is likely a high idle switch It will limit power when engaged, so remember to turn it off before you drive away. Start your truck and then flip the switch. Engage the cruise control(thats how it operates the high idle) the engine should idle up. IIRC, cruise on is 1200 rpm and resume is 1700 rpm by factory default it is for running a PTO but works perfect for warming up in the colder weather. I hooked it up on my old 2001 Dmax. Kennedy has some more info about it under tech tips. www.kennedydiesel.com

[Mark Rinker]

It could also be one of JK's custom ECMs, with two tunes installed. Try contacting John Kennedy to determine just what you have there. If its a tiny little chrome toggle switch, I am betting you have one of his LB7 tunes.

[yukonbuck]

Buck,

You are a genius! I tried and tried to figure that thing out. I even tried activating the cruise at one point while sitting still but i didn't hold on the button long enough. After your post I went back and fooled with it some more and behold, a high idle switch it is. I just had to hold down on it longer than i did before. Makes sense why it's there since i do live in AK. By the way that truck pulls harder than any 7.3 ford of the same year hands down. I should know i test drove like 10 fords before i fell in love with my gmc...

Thanks again,

Yukonbuck

[Buck]

You don't have to hold the button. Go to www.kennedydiesel.com and click on tech tips then duramax tips then fast idle installation instructions LB7. There it will give you a complete description of how it works.

[Crooked Hole]

does anyone know if there is such an option for the 2007 LBZ?

[Buck]

LBZ already has it "elevated idle" in the DIC use the steering wheel button "i" to find it. if you don't have steering wheel buttons you have to turn on the key pump the pedal....it is in your owners manual.

[Crooked Hole]

This is an automatic system and does not work once the vehicle is warm, looking for A manual high idle like they are talking about in previous post.
Unless there is A way to turn the idle up that I am missing in the manual.
Apparently on some van models there is A switch for this feature.