LML Allison acting up

[Huffy67]

My dad has a stock '11 LML with about 125k on it. He has only owned it a few months and the Trans is starting to act up. Sometimes if you take off from a stop light it's like it's in neutral for a second or two, then jumps in gear and takes off. Sometimes if you back out of a driveway and put it in drive it feels weird and doesn't want to go, then jumps in gear and takes off. I know the LML Trans is different than previous years. Anyone know what it could be? I can't imagine the Trans would be going out already. It was perfectly fine for the first couple months, he serviced it prob two months ago and it has just recently started having these symptoms.


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[melms23]

Did he change the transmission oil in during the service? My LMM is VERY touchy and tough to read on the dipstick. They do some odd stuff when cold if theres not enough fluid in it.

 

[Huffy67]

I meant he serviced the transmission, not the engine. I'll check the fluid on it tomorrow.


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[Awenta]

Was the nsbu switch an issue with these?

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[duramaxzak]

They had some problems with the TCM on the 11's. I had a bad TCM destroy my tranny at 64,000. GM covered the tranny, I had to pay for the TCM. Apparently something with a bad internal ground within the TCM causes the problem. I started getting some codes and it wouldn't down shift when you came to a stop and take off and than sometime's you would put it gear it was like it was in neutral.

 

[mike diesel]

Was the nsbu switch an issue with these?

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The NSBU is internal and rarely have issues on 06+ trucks.

 

[Mike L.]

Sounds like low fluid or internal filter problem.

 

[Huffy67]

Fluid level looks good. Guess we will try a new internal filter.


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[Mike L.]

Fluid level looks good. Guess we will try a new internal filter.


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Peel open the sump filter and see what's in it. Post a picture here.

 

[Huffy67]

Peel open the sump filter and see what's in it. Post a picture here.

Will do sir!


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[melms23]

I also had trouble getting a filter from oreillys to stay up with the o ring. My fix at the time was a filter lock but i now know and will have an actual allison filter next go around.

 

[juddski88]

I have had issues with the '11+ style Allison filters too, just an FYI. No issues to date with the older 5sp style, even some better non-Allison brands.

 

[Hoffie]

My transmission just went into limp mode on Thursday just 3 miles from a dealership.
They found the wiring harness insulation had cracks in it and let tranny fluid into the wiring connectors. They had to replace the wiring harness, a couple of sensors and the TCM. They also changed the fluid and both filters.
Funny thing, I had just had the tranny serviced last month with new fluid and filters.