Allison 5sp: Hit lockup switch lock button, loud bang, limp mode, codes, strange noises....

[thunder550]

Hit lockup switch lock button, loud bang, P0776, strange noise....

I was testing a new BT lockup switch in my LLY that I got from Ben this afternoon to make sure everything was working correctly.

Left a parking lot, got on it probably 50-60% throttle, hit the Lock button when I was going probably 45-50 mph, and BANG....loudest and harshest shift (I'm assuming shift, I doubt a converter could lock that hard, unless I got a combination shift and converter lock at the same time) I have ever felt. Trans felt like it went to neutral (engine would free-rev), CEL popped on (P0776), DIC showed Range Shift Inhibited. I was able to pull over, shut the truck off, clear codes and drive, but when it tried to shift either to 3 or 4 (not sure which), felt like it went into neutral again and CEL popped on again, same P0776 code.

This all happened about a mile from my house so I limped home. Put it into R to back into the garage, it hesitated for a second then kind of shuddered into gear and I was able to back up. Put it in P in the garage, opened the door to listen, and there's a kind of mixed growling/scraping sound coming from underneath at idle.

How bad is this thing F'ed up? I'm assuming I toasted a clutch pack or two at a minimum based on what I've read, but I also saw an older thread that talked about losing a planet and hub as well.

Also, most importantly, how the hell does locking the converter manually cause this? What did I do wrong, and what should I know better for next time?

Mike, I'll be calling you in the morning to set up some time to come see you again, just would like to get an idea what the hell happened.

 

[hondarider552]

In for the road trip. Call ya tomorrow Chris.

 

[mike diesel]

P0776 and limping going into 4th+ gear...you broke the p2 planet snout or stripped the c2 hub more than likely.

 

[duratothemax]

Chris is that the first time you hit "lock" with the new box? Im extremely confused here. I ran that exact box in my own truck (05 LLY) for a few days just to make sure everything was all good with the newest design.

Ben

 

[thunder550]

I hit it when cruising at 40-45 mph a few minutes earlier with no problem, everything worked as it should then. I sped up to about 55 and let the converter lock on its own, then hit the unlock button, that worked fine too. Lock and unlock both were fine. I did not have a chance to test the WOT/ auto function but it worked fine in the previous box and my main concern was whether the box shut off when the TCM commanded lock up like before.

I drove the truck to taco bell, tested that it stayed on during TCC lockup command, sent you the PM while sitting in the drive thru, then broke the trans about 3 minutes later on my way home, lol.

 

[thunder550]

FWIW I am not pointing my finger at the box in any way, just trying to be clear about exactly what happened when it went. In my mind I can't fathom how just locking the converter would cause this.

I have had a few random harsh shifts in the past, before installing the box. There doesn't seem to be any rhyme or reason to them other than maybe I was on it and let off right before the shift. That was not the situation this time though, my throttle input was constant before and after hitting the lock button.

 

[thunder550]

P0776 and limping going into 4th+ gear...you broke the p2 planet snout or stripped the c2 hub more than likely.

Would that explain the grinding noise at idle as well?

The TCM is tuned as well, other than shift points (speed and RPM) the only differences I saw from a stock file are in the torque reduction tables. Nothing was changed in the shift timing tables at all, those values are all stock. Could this have contributed to the problem?

 

[duratothemax]

Would that explain the grinding noise at idle as well?

The TCM is tuned as well, other than shift points (speed and RPM) the only differences I saw from a stock file are in the torque reduction tables. Nothing was changed in the shift timing tables at all, those values are all stock. Could this have contributed to the problem?

Torque reduction tables can be extremely touchy...especially under certain conditions, Ive found they can be unpredictable...seem fine for a while, and then you'll catch the trans at some "perfect" throttle %, converter slip amount, speed, etc, and it throws the TCM for a loop and you get a botched shift. Ive never broken anything, but had a couple random shifts that worried me enough to put the torque tables back to stock.

Maybe it was that "one in a million, all the stars aligned" thing where you caught the trans at a weird time with the modified torque tables, and then the converter lock combo confused the TCM to the point where it just totally screwed up the shift? Ive never once in years seen any box (whether its mine, Brayden, Tony's, etc) cause something like that.

The 3-4 shift is already hard enough for any Allison to make, so it can sometimes be touchy. What converter are you running? Is it on the looser side?

Really hard to say...but in my opinion, I definitely leave all those torque tables alone in my TCM tuning. Definitely keep us updated on all this

 

[CaptPhil]

Trans definitely needs to come out, hard parts are broken.

 

[thunder550]

Looking at the detail again, the changes are in the D5194 max torque reduction, D5195 min torque reduction, D5197 CAN torque messages, and D5196 Torque limits tables.

I'm running the Goerend/Mike L K converter.

 

[duratothemax]

Looking at the detail again, the changes are in the D5194 max torque reduction, D5195 min torque reduction, D5197 CAN torque messages, and D5196 Torque limits tables..

Ahh yep...unfortunately those are known "deadly/dangerous" tables and have been known to take out quite a few Allisons...

 

[paint94979]

My trans is from 08? It's an Suncoast Stage III built by Mike and for the life of the trans it has had the torque tables maxed out... Never an issue besides my clutches are pretty much done

 

[DMAXchris]

Chris, same thing happened to me a few years back. Right after the motor build I was merging onto the highway got in the throttle a bit, hit the lockup and BANG! Limp mode and 0776. Pulled the trans and the c3s were toast. The hub showed a little wear, but was able to be used again. No hard parts were broken.

 

[duratothemax]

Chris, same thing happened to me a few years back. Right after the motor build I was merging onto the highway got in the throttle a bit, hit the lockup and BANG! Limp mode and 0776. Pulled the trans and the c3s were toast. The hub showed a little wear, but was able to be used again. No hard parts were broken.

Chris I thought you were running TCM tuning as well?

 

[CaptPhil]

Chris, same thing happened to me a few years back. Right after the motor build I was merging onto the highway got in the throttle a bit, hit the lockup and BANG! Limp mode and 0776. Pulled the trans and the c3s were toast. The hub showed a little wear, but was able to be used again. No hard parts were broken.

Yea but his wont go into 4th gear now, and has the grinding noise at idle. Stripped hub.

 

[Mike L.]

Were the rear tires spinning when this happened?

 

[DMAXchris]

Chris I thought you were running TCM tuning as well?

Correct. I cant remember what all was changed, but after that I went to a tune with only raised shift points and lower TPS input for a downshift. It was one of pink slippers TCM tunes, so who knows what was done. Lol.

Yea but his wont go into 4th gear now, and has the grinding noise at idle. Stripped hub.

Mine wouldnt either. Had to be flat bedded down to Calebs. I didnt have a grinding noise though.

 

[thunder550]

Were the rear tires spinning when this happened?

Negative.

 

[DMAXchris]

Negative.

Mine was blowing them off at 40+ mph when it happened.

Im real curious to see what went wrong with yours.

 

[Mike L.]

Negative.

Were you having lock-up issues before you installed Ben's box? If so; you were hitting the rev limiter and the speed sensors were going crazy. When the hub and planet finally popped it was just the straw that broke the camels back. The box had nothing to do with it. The TCM tuning didn't help the situation.