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Discussion Starter #1 (Edited)
LBZ: HOW TO: Activate factory turbo brake (LMM too ;-))

Alright. I've been sitting on this for quite a few years and I've just been dragging my feet too much too get it out to the public. So, I'll get on with it.

Download:
Light Duty Elecrical manual (25-3500)
http://gmupfitter.com/files/media/photo/99/2006_LD_CKFullSizeElectrical.pdf

Medium Duty Electrical manual (45-5500)
http://gmupfitter.com/files/media/photo/198/2007_MD_Electrical.pdf

In the Light Duty manual navigate to section C-14 thru C-15 which are pages 72-73 of the PDF. Take note of pin 11 and 53 of the C2 connector. Notice they say unused.

In the Medium Duty manual navigate to C-21 thru C-22 which are pages 80-81 of the PDF. Take note of pin 11 and 53 of this C2 connector. This manual says:
C2 pin 11 (exhaust brake telltale)
C2 pin 53 (exhaust brake control)

This is the thing that got me to thinking 4 or 5 years ago. We all know that the '06 and '07 MD trucks that have the RPO of LLY are actually packing an LBZ engine with an MD tune of only 280hp, (or something close, or whatever) while the '05.5 - '07 classics have the same setup but have the LD tune of 360hp. So, knowing GM is all about recycling parts, programs, computers and whatever else, I wondered if they left the logic for the Turbine Brake from the MD programs in the LD programs. So, on a hope and a dream I wired up my switch according to the diagram of the '07 MD w/ RPO LLY. Wouldn't you know it actually worked. They did leave the logic for the exhaust brake in the LD ECMs. HOWEVER, the brake only activates while the TCC is locked up, eg. T/H mode activated. Also, with the exhaust brake activated it sends the TCM into a more aggressive down shifting map. Being, what I would refer to as, a power user of EFI Live I also attempted creating a .cax file to add tunability of the brake, but it turns out you need ALOT more knowledge of binary addresses and such that I don't know. I inquired a fellow from NZ who has made cax files before for gasser but he couldn't help me. I inquired with Ross too, but I never got very far with him. He is an extremely busy fellow. Enough history. Here it is. Im not going to tell you how to make a switch, and I'm not going to tell you what the part numbers are for the ECM pins. But I will tell you how it works and what you need to do to get it to work.

The way it works.

When C2 pin 53 is grounded this arms the exhaust brake. When all conditions are met the brake will activate. (vanes close to 100%) When the exhaust brake is actively braking pin 11 of C2 is activated sending 12v to a lamp if you choose. IT IS IMPORTANT to use an incandescent lamp and NOT an LED to act as the telltale. I originally used an LED as my lamp and it was causing some sort of fault with that subsystem making the brake engage and disengage rapidly, switched out to an incandescent lamp and it solved the problem.

Quick FAQ:

Q. Do I have to have EFI Live to make this work?
A. Nope. This is a factory loaded feature. However, EFI guys will love being able to have 5 tunes with and without the turbine brake instead of making one tune with the brake and 4 tunes without.

Q. Will this work on my 06 LLY/ Bosch controlled LLY?
A. Yes. I have tried it on a few different OS's and an 07 classic. I haven't ever flashed the newest, so I cant say about that one.

Q. Will this work on my '04.5 to early '05 LLY?
A. Yes and no. It (the ECM) doesn't use the turbine for braking. Instead, just like the MD's for that year range use a flapper in the exhaust to act as the brake. I have tested it and it does power a pin to activate a solenoid for the flapper valve on the LD trucks. Figure it out for your self. Apply the knowledge learned here to your LLY and you'll figure it out.

Q. Does this work for LMM's?
A. UPDATE: I have gotten a few reports now of this mod working on LMM's. One truck was an '08 and the other was an '07.5. At this point I don't have any other information as to what OS is on either of those trucks so I can't say for sure what works and what doesn't.
A. I have done very little messing around with it on an LMM years ago and I cant tell you which OS I did it on, but the logic in the ECM is there but doesn’t activate the brake. It does send the TCM into the same down shifting pattern as the LBZ but nothing happens with the turbo. Again mess with it your self maybe you can figure it out.

Happy braking!


Just for kicks here are a couple of pics to help you folks find the correct pin locations.
 

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Interesting

Thank you this is very interesting and useful.
 

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So i get it if you dont know something not to tell the guys but to just not tell them because you might some year try to make money off of it even know you already said you have been dragging your feet for 5 years already. Why dont you just give them all the info instead of half of it? Just my .02 and this doesnt even affect me. Just seems to me from your wording that you have a lot more info but dont wanna give them the info.

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So i get it if you dont know something not to tell the guys but to just not tell them because you might some year try to make money off of it even know you already said you have been dragging your feet for 5 years already. Why dont you just give them all the info instead of half of it? Just my .02 and this doesnt even affect me. Just seems to me from your wording that you have a lot more info but dont wanna give them the info.

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X2. Wtf ?

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Discussion Starter #5 (Edited)
So i get it if you dont know something not to tell the guys but to just not tell them because you might some year try to make money off of it even know you already said you have been dragging your feet for 5 years already. Why dont you just give them all the info instead of half of it? Just my .02 and this doesnt even affect me. Just seems to me from your wording that you have a lot more info but dont wanna give them the info.

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Dunno what ur talking about hommie. I just gave all the info I have. This thread is a cut and paste from DP. Seems to be a pretty big hit over there. I'm more than willing to answer any questions anyone has. I've got way too much on my plate right now to find and list pin part number or how to get them. That info is all over the place in other threads and on other websites. I guess while we are on the subject. If you have invented something or discovered something that litteraally no one has ever done before, why wouldn't you try to make a buck or two on it? Its called free market and capitalism. It makes the world go around. Anyways its free info now. So I don't know why anyone would be complaining. And I also hate how people just want to have everything (information) handed to them on a silver platter instead of doing a little research on their own. People need to think and ponder more. If they did the world would be a better place.

Happy braking!
 

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Discussion Starter #6
And you.... Why don't you give it a shot and play with it? It might work. like i said in the OP i tried it out on an 07.5 but have no idea what OS it had on it. Maybe yours is different, and it will work. Then you'd be a hero.
 

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And you.... Why don't you give it a shot and play with it? It might work. like i said in the OP i tried it out on an 07.5 but have no idea what OS it had on it. Maybe yours is different, and it will work. Then you'd be a hero.
I will give it a shot. Be pretty cool for those who don't have efi live!

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I was not complaining at all, just some of the wording made it seem like other than just part numbers you were holding back more info but giving the basics is all. And to be honest idc about the info i drive an lml and its got an exhaust brake stock. Although i do hope somebody on here does it and gets it to work and comes back with positive feedback. Good material to have for sure. I wasnt trying to jump your shit just seemed like you were saying here guys but I'm not telling you everything your gonna need to know. And yes capitalism is great.

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Discussion Starter #11
I was not complaining at all, just some of the wording made it seem like other than just part numbers you were holding back more info but giving the basics is all. And to be honest idc about the info i drive an lml and its got an exhaust brake stock. Although i do hope somebody on here does it and gets it to work and comes back with positive feedback. Good material to have for sure. I wasnt trying to jump your shit just seemed like you were saying here guys but I'm not telling you everything your gonna need to know. And yes capitalism is great.

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Maybe the OP wording does sound like that a tad. Eh, whatever I guess. I have never been one to just give people what they want without making them work for it a little.
 

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Does this mod do anything different then the turbo break i have tuned into my tow tune? would there be any advantage to doing this mod for me since i already have that tune?
 

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From what I gather it could be used while in any of your tunes instead of just your tow tune.

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Discussion Starter #14
Does this mod do anything different then the turbo break i have tuned into my tow tune? would there be any advantage to doing this mod for me since i already have that tune?
From what I gather it could be used while in any of your tunes instead of just your tow tune.

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The advantage is that it works I dependant from your tune. So you could engage and disengage in any tune you desire. AND, as stated in the OP. The transmission is sent I to a more aggressive downshifting schedule OVER what T/H already does.
 

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Discussion Starter #16
Well I uploaded them to dropbox and I fixed the original links. I borked them copying them from DP. All should be good now
 

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Discussion Starter #19
Thanks for fixing it! Any suggestions on what to try for my lmm?

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I see u have efi live. So, im sure you know that there are like a million OS's for the LMM. Wire up the switch and see if it works on any of the OS's you have. The one thing I do know that happens on an lmm is the transmission shifts WAY different than without. please try it snd report back
 

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I see u have efi live. So, im sure you know that there are like a million OS's for the LMM. Wire up the switch and see if it works on any of the OS's you have. The one thing I do know that happens on an lmm is the transmission shifts WAY different than without. please try it snd report back
I do have efilive but it was installed by a local guy..

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