Allison shifting problem.

[gr8shot]

You might try changing the spin on filter on the transmission too. It could be full of gunk and slowing fluid flow.

[jc1843]

If the check engine light came on- there is a code stored. Have the code read and that will help with the identify the problem.

[H.O.T. Diesel]

Originally Posted by Silver truck

Good day for all! My truck chevy silverado 2500 04 with duramax LB7 and allison 5speed transmission has shifting problems, when i driving at normal acccelleration the truck shifts fine but when i try to accellerate quickly it wont shift untill i back off the throttle! Before than check engine also lightning and when i try pull up from drive to neitral or parking at rear of the car i hearing "boom" and car shake.
P.S. I changed fuel filter today but it give no more.

This sounds like what my dodge used to do.. there could be junk in the valve body. Obviously you can start by changing the spin on filter. After that you can either flush it or- drop the pan, take out the valve body, and clean the junk out of the solenoids.
In my case, I did a transmission flush with filter change and it solved my problem, I didnt have to go into the VB.

As for the shifting from park, a loud noise means you probably parked on an incline. However, it could be a u-joint. You should check them immediately. You can do this by leaving the trans in nuetral (set the e-brake of course). Get under the truck and turn the driveshaft back and forth. If there is slack then you have a bad u-joint, which is usually made obvious by a bad rubber seal.

[Silver truck]

I changed transmission filter too but it give no more.

[BigRedChevy]

It still sounds like a fueling problem rather than a tranny problem. What kind of mods have you done to the truck? If you are running a tuner, what level is it on?

[dagojim]

i just went though this with my 01 and it sounds like you have the same problem the tranny is going into safe moode because its throwing a code mine had an airflow sensor go bad and sent the tranny into safe harsh mode so it doesnt have to be a tranny problem at all

[Silver truck]

Today i went to service and identify the problem, it was codes numbers: PO708, PO732A, PO776. That's problem with transmission, service man says that data unit of Allison transmission check bad signal and write that data unit check incorrect transmission gear number on 2th gear and try return transmission to warning rate.
I dont know where is that data unit.

In my car previous owner plant intercooler, perfomance chip, boost controller, data unit of gas from manifold, but dealer remove chip, data unit, boost, i think work of computer some incorrect.

Sorry for bad tech language.

[Silver truck]

i am waiting for replys

[rock04max]

How ya doin silver? The 0207 code is the number 7 injector. Most likely the connection pins to the injector is loose inside.
The other 2 codes have to do with the shifting parameters. When you fix the injector connection those codes should go away.

[ob_1jr]

My guess is the NSBU switch on the side of the tranny......but the last code is for one of the solenoids being stuck off....that would cause your sticking problems...sounds like your valve body needs a little work.