Allison 5sp: limp mode

[going bonkers]

newbie here! This is what i got, alli went into limp mode. Have been doing alot of research. Changed nsbu, still do'es it. dropped pan, cleaned valve body, changed PSM(PMS) and solenoid C put it back together and still do'es it. The codes read PO700,PO872. I clear the codes put it in reverse all good put into drive go about 3 feet an whamo right back into limp mode. Can (Somebody HELP me). Right now i'm checking for a possible short to ground but don't know where to start. The truck is a 03 silverado w/alli 1000.

 

[JoshH]

Sounds like a sticking E valve.

 

[Mike L.]

Sounds like a sticking E valve.

That means there is damage in the trans.

 

[going bonkers]

Thanks for replying guys.. so it looks like i drop the pan again check the E valve and MikeL what kind of damage am i looking for??? in the valve body

 

[Mike L.]

Thanks for replying guys.. so it looks like i drop the pan again check the E valve and MikeL what kind of damage am i looking for??? in the valve body

What's the history on the trans?

 

[going bonkers]

Never no problems except letting my 19 yr old take up north with his buddys and of course they get it stuck.

 

[going bonkers]

I know they did alot of rocking an rolling to get it out and the boy said thats when it went into limp mode

 

[going bonkers]

found the e valve. going to pull valve and have it rebored and new parts. one post said possible weak spring but im gonna have it done right all new parts

 

[DBUSHLB7]

Sounds like a plan. Keep everything clean clean clean. Slightest bit of debris can cause headaches.

 

[Mike L.]

I know they did alot of rocking an rolling to get it out and the boy said thats when it went into limp mode

They probably did some clutch damage. This could be a never ending battle without pulling trans.

 

[going bonkers]

Thanks guys

 

[Taylor-34]

Oh I can wait for the day I have to deal with my two boys beating on their trucks and me having to fix em ugh... Good luck with the project keep us posted

 

[going bonkers]

JoshH U hit the nail right on the head. Took the valve body down to have check out and the guy said U were right it was a sticky E Valve. So I decided what the heck re-hone all the bores. A BIG thanks for the info.