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2500hd Allison Probs 8.1l


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Posted

OK I need some insight. Came home yesterday from pulling my 25ft 7000lb 5th wheel back from camping, only like an 1 ½ drive. Drop my trailer off at storage. Go back into town and drop off friend at there house. After unpacking them started the truck up and had no reverse. Paniac totally kicked in as I am about to go on vacation here very soon.

I threw it into drive but I don’t think it moved either(I was freaked out at the time and cant remember now). So I turned of the truck turned it back on and no reverse. Totally starting to freak out I turned it off again pull the shifter threw all the gears a couple times , started it back up and everything was working again.

You also get some really loud clunks going into park and drive some of the time, but mostly park. I know somebody out there posted theres has aloud clunk too into park.

 

So can anybody chime in? Am in trouble I don’t have the money for a rebuild, could it be linkage. After driving it home it grabbed every gear perfect and no slipping, tranny fluid is all the way to the top of the cross marks, doesn look burnt and nice and clean. Truck only has 64k miles and does not get beat.

 

What do you think please let me know as I leave soon for vacation and this is freaking me out!

Posted
OK I need some insight. Came home yesterday from pulling my 25ft 7000lb 5th wheel back from camping, only like an 1 ½ drive. Drop my trailer off at storage. Go back into town and drop off friend at there house. After unpacking them started the truck up and had no reverse. Paniac totally kicked in as I am about to go on vacation here very soon.

I threw it into drive but I don't think it moved either(I was freaked out at the time and cant remember now). So I turned of the truck turned it back on and no reverse. Totally starting to freak out I turned it off again pull the shifter threw all the gears a couple times , started it back up and everything was working again.

You also get some really loud clunks going into park and drive some of the time, but mostly park. I know somebody out there posted theres has aloud clunk too into park.

 

So can anybody chime in? Am in trouble I don't have the money for a rebuild, could it be linkage. After driving it home it grabbed every gear perfect and no slipping, tranny fluid is all the way to the top of the cross marks, doesn look burnt and nice and clean. Truck only has 64k miles and does not get beat.

 

What do you think please let me know as I leave soon for vacation and this is freaking me out!

 

 

was it really wet while towing home? I know on mine I had a problem with the neutral safety switch that gave me almost identical symptoms was worse when it was wet out, there is and updated design from GM to replace it

Posted

No it was really warm. On the other site i posted somebody also said it might be NSBU switch is the same thing you are talking about? Is it very espensive? Hate to replace it to find out it wasnt that. But thanks for your input i really appreciate it. Im going on vacation soon and dont want to get stranded.

Posted

The old NSBU switch is black, the new one is tan. I had mine replaced awhile ago, same problems and eventually ended up limping it to the dealer doing 30mph. It is a TSB item. Do a search and find some posts on it. There should be some pics.

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