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I have an 05 crew with juice/attitude. I keep reading about "limping".. What causes it? What happens then? How does it get fixed? Motor and tranny act the same?

Ive run 5/5 about 3-5 times, 4/5 10-20 times and drive in 3/5 most with no badness for about 2 weeks. Do I dare run above 3/5 as long as I dont mash the pedal from a dead stop?

Thanks
 

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edge recommends not using level 4 and 5 without tranny mods done. tranny has to learn with each new power level, when it limps it will limit your rpm's to 2000 and the only way to clear it is to pull over, turn engine off for a few minutes, then start it back and its good...until you do it again.

I'd suggest doing a search of "limp mode" and kick back and do a bit more reading.

good luck
 

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Mine did it with Banks set on 6, W/O throtle in 5th and soon as it tried to lock TC cluth it "limped". What happened? It automaticaly downshifted to 3rd and stayed in 3rd until I pulled over and cycled the key, SES light was on for a couple days.
 

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Is the Edge juice that much stronger with the LLY engine that it limps the Allison?

I just traded a 01 Duramax with the Hot Juice, Drive was always the 125 hp program. Never once limped the truck. Once and I while I would run it real hard off the line but usually had my foot out of it before it hit 5th. I would also roll it on hard in 5th for passing. For towing in tow mode it was the 60hp program.

Never had a problem in over 100,000 miles with the juice.
 

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The Edge isn't stronger but the Allison is weaker.GM's plane to make it consumer friendly and take the commercial duty out.Good idea except for the ones that want to juice it up.


Limp mode is fail safe in the Allison.

1) It will default to one forward gear,3rd I believe in most cases on a stock Allison.
2)You will lose reverse.
3)SES light will illuminate.

To reset IN MOST cases.Pull over shut truck off and let it sit for a few minutes.Restart and it should have full gear range.

SES light will need to be reset or it will continue to illuminate until so many on off cycles of the ignition and no new code.Codes will be stored in ECM and TCM till cleared.

The more you over torque the Allison the easier it will limp as your slipping clutches each time.

Go floor it! :D





*If it effects RPM it isn't transmission related fail safe.Yes the Duramax will cut power when something is a miss too,but that's a different issue then being discussed here so as not to confused.
 

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Mackin said:
The Edge isn't stronger but the Allison is weaker.GM's plane to make it consumer friendly and take the commercial duty out.Good idea except for the ones that want to juice it up.
Ain't that the truth!
 

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Mackin, you will have 3rd and reverse. This is built into the Allison so that you can "limp home" if need be. These ranges are possible without electronics, i.e. pulling the main transmission connector off the trans enables limp home.

Assuming you haven't fried too many clutches. Can't remember which clutches are engaged for 3rd & reverse off the top of my head.
 

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Mackin said:
The Edge isn't stronger but the Allison is weaker.GM's plane to make it consumer friendly and take the commercial duty out.Good idea except for the ones that want to juice it up.
That suck. Taking the commercial duto out is a bad idea in my opinion.:badidea: The commercial duty allison was the big selling point for me in 01. That is also why I did not even consider the others in 05. Why would GM take the commercial out, these are trucks, not SUVs for soccer moms.:rant:
 

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GM put clutches and pressures in to handle 605TQ? at the crank. You always match the trans for the application. It holds very well at the stock power level. However, the bigger tuners run 1200TQ+ at the crank. Few (if any) stock transmissions will hold twice the torque without modifying them. It was not a mistake, it was designed as a matching system.

When you think of what you must do to get the Allison to hold twice the stock power, it's really not that much. No "hard" parts are required.
 

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Tranny work

How much does it cost to have the tranny done to handle the power?
I'am a new diesel owner as of today and I'm already looking for more power. I really bought this truck to tow but I'm a gear head at heart.

What is a safe hp level to run on a stock 05 duramax and still have that rush in the butt-dyno? I'm no stranger to modding my cars. My wife drives a 300hp turbo volvo at 18psi and I just sold my 320hp 13 sec eclipse. Any help would be greatly appreciated.
 

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Mackin, you will have 3rd and reverse. This is built into the Allison so that you can "limp home" if need be. These ranges are possible without electronics, i.e. pulling the main transmission connector off the trans enables limp home.

Assuming you haven't fried too many clutches. Can't remember which clutches are engaged for 3rd & reverse off the top of my head.
Incorrect.

Allison has many different limp modes and also has shut downs. You can lose forward or reverse, or both depending on what the TCM reads and what actually fails. When and if your Ally goes into no movement mode, you will need a Tech 2, Mastertech 3100 scanners to clear these codes. SnapOn will not do it. Funny thing is, an AutoXray ( 200.00 scanner) will.
mike
 

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All Snap-on scanners? I have a Microscan, one of the low end ones that Snap-on sells, and it clears my trans codes.
 

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GM put clutches and pressures in to handle 605TQ? at the crank. You always match the trans for the application. It holds very well at the stock power level. However, the bigger tuners run 1200TQ+ at the crank. Few (if any) stock transmissions will hold twice the torque without modifying them. It was not a mistake, it was designed as a matching system.

When you think of what you must do to get the Allison to hold twice the stock power, it's really not that much. No "hard" parts are required.
please continue with more info on what is to be done for the tranny to hold up, thanx
 

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please continue with more info on what is to be done for the tranny to hold up, thanx
Do a search on Suncoast, ATS, and you will find more info than you bargained for.
 

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Actually Brayden and Mike L are both correct. If you are driving and the transmission cannot make an upshift or downshift due to some malfunction of the range it's trying to go to then it will default to the previous range and stay there. However, if the transmission controller loses power or the transmission becomes unplugged then you go into hydraulic default which is 3rd and Reverse. This default is pure mechanically controlled hydraulics and uses the C1 and C3 clutches for 3rd and C3 and C5 for Reverse.
 

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Thanks Machinator.

YOU are correct. There are several modes of failure. Fail to range, etc.

Limp home is actually only when the trans drops lockup and fails to 3rd, and only allows 3rd and reverse. The others are Range Inhibits. Many people have started to call every GM failure mode "Limp Mode". But the allison coined phrase actually is describing the 3rd and reverse hydraulic mode of the 1K/2K/2400 series trans. It's self explanatory.

Limp home mode.. Let's you limp your vehicle home in case of electrical or certain mechanical failures.

There's actually a procedure called out in the troubleshooting manual for limp home. I pull the main trans connector everytime I have a trans with no codes show up. If it doesn't have 3rd or reverse (limp home mode) then there is something wrong internally.

Oh, and if you have the Allison software you can clear it too! ::muahaha:
 

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I limped mine twice....shame on me....and it went to 4th gear both times.
 

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If you only have 3rd and reverse, isn.t that range inhibit? If you are stuck in 4th gear, aren't you limping? I can cut a wire off the NSBU switch and your theory of pulling the connecter will not work and your Allison DOC will not show it. It will give you an erronious code and lead you on a wild goose chase. If you build a high performance Allison and have problems, you can take most of what you see in the manual and ignore it as far as diagnosing.
 

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Per Allison Lingo.. Limp Home is only the hydraulic 3rd and reverse mode.... That's it..

If you are stuck in 4th gear, no it's not limping.. It's called a "fail to range".

If you cut any wire in the LCT harness you'll get a code. NSBU will show a parity error if you cut a wire. There are certain states that the TCM monitors on the NSBU, and if it gets no state change on an NSBU wire then you get a code.


EDIT: You need to read my posts a little better before you post.. Everything you posted is out of context and really makes no sense.

As for pulling the main trans connector. It's just good practice for when you don't have any codes. It will tell you if you're chasing intermittent electrical problems or a hydraulic/mechanical problem.

Allison DOC will tell you everything you need to know, you just have to be competent enough to interpret the data.


Mike many people think highly of you here, and I'm not bashing.. But you really need to think before you post some of this crap. You need a much better understanding of Allison controls before you try to convey information to people. :rant:


Also a high performance Allison will diagnose just as easily as a stock one. Why would there be a difference.
 
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