Allison 6sp: Strange acting in T/H

[Big Chris]

The transmission in my LMM has been acting wierd. In tow haul when grade braking to a stop the torque converter does not maintain lockup. Occasionally it does but most of the time not. Sometimes it will unlock then lock back up very harshly as you might expect. It acts normal accelerating or up shifting. I changed the internal filter, spin on, and put new fluid in it and it still acts up. No codes that I can see with my V2. Transmission is 100% stock. My guess the converter is failing??? Thanks in advance for any help. I should add it's never seen more than an 80 rwhp tow tune and I tow anything heavy on a 40 rwhp tow tune.

 

[oscyjack]

When does it unlock? afaik It will unlock on it's own as you decelerate below 25 mph. I'm usually unlocked by the time the 2-1 shift occurs. Same as when you start off, it'll be unlocked and then lockup right about 25mph in 2nd

 

[Big Chris]

Way before that. Usually over 40 mph.

 

[oscyjack]

Yeah id say thats early. Im by no means an allison expert but usually when I have an issue I just initiate a re-learn and it seems to do the trick. Wish I could be more helpful

 

[Awenta]

Yeah id say thats early. Im by no means an allison expert but usually when I have an issue I just initiate a re-learn and it seems to do the trick. Wish I could be more helpful

That's a mistake


Sent from my iPhone using Tapatalk

 

[oscyjack]

Don't matter much as i'm chatting with Evan this week Just been doing what I can to make sure it survives til then!

 

[Big Chris]

Actually the converter unlocks when coasting to a stop at about 40mph when not in tow/haul as well.

 

[Mike L.]

Clearing the TAP's to solve a problem does no good. It was never invented to do this. It will set the adaptive memory to zero which will hide the problem because the TCM will no longer remember what it did to try and help the problem. In a short period of time the TCM will adapt to said problem and start all over. Resetting TAP's is only used to clear the memory on a fresh build because the TCM does not know what was done to the trans. It begins to adapt to the new mods after a build.

 

[oscyjack]

Good info Mike, thanks.

I guess i'll at least rephrase what I meant as it applied to me, but what you said obviously makes sense.

I hadn't cleared the TAP's once since I bought the truck. After adding quite a bit of goodies and tunes etc, and still having some weird driveline clunks/bumps/vibes I decided to use the edge to re-learn. Didn't go 10 miles when my dog slipped on the center console, and he weighs 100lbs, so naturally he fell onto me, which sent me off the road some. Long story short, I needed an alignment and for whatever reason I can't have things not line up how I think they should be. So I cleared the taps again when leaving the garage. Truck has been running much better since that but it was only my second time clearing them in a s many days

So, OP, I gave you bad advice it seems. It was given to me by someone else who does not have the same knowledge as Mike.