Hi, this is my first post and I need your help. I bought my truck about a month ago GMC Sierra 3500, Duramax with Allison trany, duallies with 34,000 miles. I bought this car from the dealer acution and I thought it was good deal but now I have second toughts. When I pick up the car I notice some vibration between 50 and 60 mph only under accerelation. You could no feel them when you were slowing down. I took it to few mechanics,trany place, and dealer, and nobody knew from where those vibrations were coming. I had wheels balance but did not help. Today driving home my car when into the limp mode, only 3rd gear. I read the codes and I had the following PO872, PO875, PO700. I check the trany fluid and it is fine. Are those 2 issues related? Any sugestions? Turck has little over 35,000 miles, now.

Thanks for your help

P0875 is E Solenoid.
P0875 is Reverse presure switch. (I believe)
P0700 means that the TCM has set a code, one of these or some other P07xx's that only a couple of code readers will see.
I not a tranny expert (but I had mine rebuilt). I would start with checking all the conectors and pins. Is your truck still under warrenty?
Post a sig, helps when diagnosing problems.

And Welcome to the site. Just a warning...hide you Credit cards....this place can be expensive...

Hello, im new here dont post to much but i have a 05 dually diesel crew cab and my allison is showing the same codes it's been to 3 different dealers and 1 of the dealers 3 times. there remedy for the problem is to reset the code and send me off. miles down the road when my 3-4 car trailer is connected it will blow codes and go to default mode, overheat. since the technicians at the dealership can never get the transmission into default on their test drives they'll blame it on the banks big hoss performance. reset the code and out the door i go truck still not fixed transmission damaged. problems started occurring around 8000 and now where at 21000.

titanchief
"since the technicians at the dealership can never get the transmission into default on their test drives they'll blame it on the banks big hoss performance"
Odds are your problem is the Banks.
Do a search for "I limped it".
Your pushing the tranny beyond it's design.

wanadmxsub, thanks for the search but i was unsuccessful with finding someone who limped it with the same problems. Have you heard of banks being a problem with these allisons? To the best of my knowledge i thought banks monitored the transmission for slippage so if there was slippage it could defuel it as a protection. Wannadmaxsub i understand that the tranny would be pushed beyond its design while in default mode or is it the way its being worked pushed it into default .thanks..

Titanchief, when you take your truck to the dealership to have warranty work done always take your banks off. Absolutely the banks is the cause of your problems, it does have a built in tranny protection but the allison is a little more touchy, what level do you run the banks in?
create a sig for yourself so we can see what you have

durymcgee, when i am towing i am normally in level three. Thank you for the reply i will be creating a sig soon.

Stuck E shift valves have been extremely common. Sonnax has a reamer that they say fixes the issue in the VB, plus they put a stiffer spring behind E shift valve.. I'd try it if you are out of warranty. If not take your chips out and go to the dealer.

id be careful towing in level 3...JMO..

--Ben

Slippage is slippage and it hurts the tranny. The tuners that defuel just let you get away with it longer. There is a saying around here..."If you want to play, you must pay".
If your in the SO Cal area MikeL is the guy you want to talk to.

thanks for the input guys, next time it acts up before i go to the dealer i'll make sure its removed not just dissconnected,"If you wanna play,you must pay" you guys know its no fun if you pay more than you play. It was mentioned to watch towing in level 3, I thought that was safe level unlike towing 5/6.