[superchevy32]

hello, i just got through replacing my allison in my 2003 Chevy Silverado 4x4 with a duramax and an allison. i need help please from anyone that has had this problem: started when everytime i would drive and hit a bump the transmisson would slip out of gear, problem got worse and finally just stopped working. (popping po734,po735) all kinds of codes like these. my banks says that the control module is bad when the engine light comes on, i have been told that this is like a default code for the engine light to come on, it is also saying on the dash that the "Range Shift Is Inhibited". so i replaced the allison with a brand new one, replaced NSBU switch, everything, now the truck will not go anywhere in 2Wheel drive, or 4 Wheel drive HI. but when you put it down in 4Wheel dirve LO it pulls just fine, same thing as when i pulled it apart. also when its in 4wheel HI and 2wheel HI and you go from any gear back to park it grinds like if you where rolling and put it up in park before it stops rolling. Given this i have thought about it and the only conclusion i can come down to is that it has to be in the transfer case, REASON: the input and output shafts to the tranny are spinning and the drive shaft is not, which means that when you hit your brakes to make the output shaft of the tranny stop moving to put it in park, its not stopping it

DOES anybody know of anything in the transfer case or anything that could cause this, I NEED HELP PLEASE!!!!!!!!!! THIS IS GETTING REALLY REALLY EXPENSIVE!!!!!!!!!!

IF YOU WANT TO JUST CALL ME IF YOU HAVE ANY IDEAS:::::
903-870-8076

 

[Machinator]

I think you are on the right path. The two codes you list above are incorrect gear ratios. The control module calculates the transmission ratio by dividing the input speed into the gear box (not the same as converter speed) by the output speed. In your case the output speed is provided by the T-case. If there's some sort of mechanical and/or electrical problem with the T-case it could be what's preventing 2WD/4WD-Hi and the transmission codes.

 

[Teck]

where you located, know a good 4 wheel drive guy in DFW area.

 

[superchevy32]

i am located in Sherman Texas about an hour from dallas. any help would be awesome

 

[Cobra#3747]

Pull the top plug on the transfercase and check the fluid level. If you can get any out, put a pan under it and pull the bottom plug and check it. Should be red and about 2 quarts of fluid in it.

Uses ATF (Dex III) for FYI

 

[Teck]

I will see if i can get ahold of him today & see what he says about your problem, let you know if he can help.

 

[wawa]

check the 2-4 range fork inside the trans. if the fork is worn out it could result in the t-case popping out of 2hi or 4hi resulting in the condition you are experiencing