Allison 6sp: Possible limped transmission

[ICEMAN]

Driving my truck last night got into the throttle a little (about 3/4 throttle) with it on the 90 horse tune and my transmission hit fourth harder than usual and fifth harder too then dropped right back to fourth gear and wouldn't shift past it. I was a mile from home and just got home. Went to back in the garage and had no reverse. Figured I had limped the trans so I shut the truck off and restarted it and didn't have any gears at all. Cycled the key a few more times (showing "range shift inhibited"), the truck clunked hard in drive after a few times, and I had all my gears again. Parked it and checked codes and the only codes the Flash scan read are P0116, U1000, and a U1301. My CEL has been on for a while (for glow plugs not working) and doesn't show any of those codes to be there. So my question is do any of these codes mean I limped my trans?

I have had a hotter tune on it and run it harder than I did last night with no issues, so I am just looking for a little more info on what I did to my truck. Thank you in advance!!
Matt

 

[xtremebikr04]

Sounds like you limped it to me. Did you happen to get the codes?

 

[ICEMAN]

Those three codes were the only ones I could pull off of it. From what I've read the flashscan V2 should be able to see TCM codes or am I missing something?

 

[TexasRob]

I remember reading somewhere that the U1000 code was in a bulletin. I think it is probably from lack of communication to your TCM

 

[Max Attitude]

Back when you first got the truck…I couldn't get the Predator programmer to connect for some reason. Maybe related? EFI went in fine though right?

 

[ICEMAN]

Yea that was the only problem I have ever had trying to flash it and it wasn't that big of a deal then. So the theory then is my TCM lost communication for a brief moment with the rest of the truck and got thrown into limp mode? Seems kinda weird

 

[NKlamerus]

Have you checked the NSBU switch and the connections?

 

[ICEMAN]

I have not. I believe the NSBU switch is inside the trans on the 6 speed, but I'll crawl under there tomorrow and see if any sensors/ wiring is smashed.

 

[NKlamerus]

Very true. And you may need to unclip some harnesses and spray them with corrosion x, I bought my truck from chicago and I live in florida. I definitely have one of the rustiest trucks on the road down here and those harnesses were s.h.o.t., thought I learned my lesson with my first truck...guess not...New harnesses ain't too cheap or fun to replace, I had a p0703 and a u1000, codes were gone for 3 months then came back

 

[Max Attitude]

His is a southern truck. No rust yet but that doesn't mean there won't be corrosion in harnesses.

 

[ICEMAN]

Alright just took it out again, checked the fluid it smelled a little burnt but seemed to shift through all the gears like it should. Finally accelerated like I did the other night and same thing 4th - 5th drops it into 4th and won't shift past it. Cycled the key a few times it would clunk into drive but then say "Range shift inhibitted" and wouldn't let me go anywhere. Finally hooked up with the V2 and showed P0777 and P0700 cleared the codes and drove it the rest of the way home. So I now know I limped the transmission, but do these codes show any specific information as to how bad I damaged it?

 

[Evan@InglewoodTrans]

You hurt it pretty bad p0777 is not a good code to see. Your having a tie up.

 

[xtremebikr04]

You hurt it pretty bad p0777 is not a good code to see. Your having a tie up.

Is that referred as the death code?

 

[Evan@InglewoodTrans]

Is that referred as the death code?

Heart attack

 

[ICEMAN]

So I did some reading and there are some posts that say it could be multiple things causing the tie up (Trying to think optimistically ). Apparently it could be a bad speed sensor, or wiring, improper clutch clearance or damaged tone wheel on the front rotating assembly or transfer case. Other than the obvious, change the spin on filter to look for shiny stuff and looking for damaged wiring, what other things should I do to try to pin point the problem?

 

[Max Attitude]

If it's your trans we could have a build party this yr.

 

[Mike L.]

Put a Tech 2 on it and watch the turbine and output speed sensors. Lock it in 4th and watch. The numbers better be the same . Next run it through the gears and see if there are any glitches or drop outs on these 2 sensors.
Check voltage to the solenoids. The start getting goofy below 11V. Disconnect main harness at the back of trans and see if it's oil soaked.

 

[danzick]

Ive limped my transmission before and it cause the range shift inhibited to show up. I also limped it quite a few times on an old predator 80 HP tune. Id say turn it down if you going to beat it up, or dont drive hard in the higher gears.

 

[danzick]

Put a Tech 2 on it and watch the turbine and output speed sensors. Lock it in 4th and watch. The numbers better be the same . Next run it through the gears and see if there are any glitches or drop outs on these 2 sensors.
Check voltage to the solenoids. The start getting goofy below 11V. Disconnect main harness at the back of trans and see if it's oil soaked.

when My local builder was rebuilding mine, he was being pushy about replacing the speed sensors while it was out. Do they fail often? I know they didnt cost a lot.

 

[Mike L.]

when My local builder was rebuilding mine, he was being pushy about replacing the speed sensors while it was out. Do they fail often? I know they didnt cost a lot.

I agree with your builder.