i have an 04 lb7 the trans stuck in third. i changed the nsbu switch, cleared all the codes and i have the same problem. It has reverse but it clunks kinda hard. has the shift range on the dash still seems everything is fine there. Any help would b nice id like to fix it myself then have a dealership do it.
Allison 5sp: trans stuck in third but has reverse
- Thread starter corey423
- Start date
whats done to your truck? fill out your sig. but it sounds like its in limp mode, and did you do your nsbu in neutral.
Yeah that's limp mode, when and how did it happen? Was it just driving normal or being a little hard on it? I have been fighting mine with same issue for a month now. What codes came up?
the truck has efi, a fass, a 4in exaust, intake, and a honed out intake horn, i wasn't being too nice on it. i was pulling on another truck that was broke down it was muddy and all that was makin it move was wheel speed so that said i was spinnin hard on it, and it went in limp mode. i got home and cleared the code and the same thing. i checked the ign fuses put the new nsbu in it. No diffrence once i clear the codes it shifts great till fourth it wants to go in fourth but once it does it seems its in netreal then throws a cel. the codes are a p0700 ''limp mode'' then a p0776 says pres ctrl solenoid b perf/stuck off , im decent on mechanical stuff but im lost seems like a electrical situation, im going to have my trans built soon but i wana figure it out first so i dont put it back in and have a good trans that still doesn't shift. it was a southern truck they pulled campers with it all its life with 250k miles so i know it needs some help ive had it for a year and put 4000 miles on it and its been broke since december its gettin warmer and im wantin to get it drivable again
YOu could try to drop the pan and the valve body. Clean the vb out by removing the valves and spray brake parts cleaner in the passages and blow dry with compressed air. You may have a hung valve but most likely your trans is cashed. I had an lb7 efi setup similar to yours and lets just say 4th gear and up are no longer with us. I put another trans in and am getting close to building the one I trashed. Good luck.
07dirty
2.5 mafia 1k hp.
The p0776 code indicates a tie up. 2 gears at once. Possible speed sensor issue or transfer case. Could also be trans giving out.
07dirty
2.5 mafia 1k hp.
You're going to feel stupid and pissed putting a trans in and finding out it's something else. If it happens I won't say a word; I'll just post a winky.
07dirty
2.5 mafia 1k hp.
Theres 2 speed sensors. There for reading input and output speed. One could be bad. Im guessing t-case could be binding up causing the tranny to get hot and slip. But not positive. Mike L could answer that more thoroughly.
oh i know thats why im on here askin you guys i wana be 100% shure i need a trans befor i blow my money on somthin not needed. Where are these sensors located and what needs to be done to test these. i went from a 12 valve to a duramaxso i got a lot to learn. Any ideas you guys give me ill try to narrow it down and get it resolved
07dirty
2.5 mafia 1k hp.
Im not positive on the allison off the top of my head. Im a toyota tech. But normally there on the side of the transmission housing. Should be black. And they will be identical to each other. The connector side of the sensor should face each other. Alot of time u can do a resitance check. But i dont know the +/- range resistance for it. U might just have to replace the sensors and see what happens. Im thinking since ur speedo works and if it is a sensor problem it will be the sensor closes to the bell housing not the tail shaft. U could buy one sensor. Replace the front one closest to bell housing then if that dont fix it put the old one back in and replace the sensor closest to the tailshaft.
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07dirty
2.5 mafia 1k hp.
