Allison 6sp: transmission shift inhibited

[Pwinland95]

I have an 08 LMM with the allison 1000 6 speed tranny. A month ago the truck lost signal and the it wouldnt stay in reverse. "Shift inhibited, N to reset," came up on the dash. I shut the truck off for 15 minutes, restarted and everything worked. Last week, i was leaving work for lunch and truck kicked out of Drive twice. The tranny regained signal and i was able to drive it. Yesterday morning i had a problem with reverse and drive for about 5 minutes. local dealership hooked it up to their computer and said the TCM is fine but the internal wire harness needs to be changed. We unplugged the outside wire harness from the tranny and there was a little bit of fluid in the pass through connector. My question is, is there an internal seal i can change on the wire harness prongs going into the pass through connector or do i need to buy a whole new internal wire harness.

 

[Bdsankey]

I have an 08 LMM with the allison 1000 6 speed tranny. A month ago the truck lost signal and the it wouldnt stay in reverse. "Shift inhibited, N to reset," came up on the dash. I shut the truck off for 15 minutes, restarted and everything worked. Last week, i was leaving work for lunch and truck kicked out of Drive twice. The tranny regained signal and i was able to drive it. Yesterday morning i had a problem with reverse and drive for about 5 minutes. local dealership hooked it up to their computer and said the TCM is fine but the internal wire harness needs to be changed. We unplugged the outside wire harness from the tranny and there was a little bit of fluid in the pass through connector. My question is, is there an internal seal i can change on the wire harness prongs going into the pass through connector or do i need to buy a whole new internal wire harness.

Merchant Auto makes a kit to reseal the harness but I personally haven't had great success going that route on the few occurrences a customer brought me that kit to install. I would personally replace the harness.

The Allison PN for the harness is 29543336.

 

[Pwinland95]

Merchant Auto makes a kit to reseal the harness but I personally haven't had great success going that route on the few occurrences a customer brought me that kit to install. I would personally replace the harness.

The Allison PN for the harness is 29543336.

Forgot to add that we did replace that seal from merchant. Figured as cheap and easy as it was that it would be worth a shot. No luck

 

[Bdsankey]

Forgot to add that we did replace that seal from merchant. Figured as cheap and easy as it was that it would be worth a shot. No luck

If there is still fluid in the connector then you'll need to replace it. If you need a harness give me shout and I can get something shipped out.

 

[KyleC4]

FWIW I’ve seen those year trucks have a little bit of fluid in that pass-thru connector and it still be a TCM problem.

 

[Bdsankey]

FWIW I’ve seen those year trucks have a little bit of fluid in that pass-thru connector and it still be a TCM problem.

Yeah, it is definitely a possibility that him and I have talked about.

 

[Pwinland95]

So just a little update in case anyone wants to know.. replaced the internal harness last Sunday and so far the truck hasn’t had any issues. Even shifts better. Thanks bdsankey for the parts :thumb:

 

[Bdsankey]

So just a little update in case anyone wants to know.. replaced the internal harness last Sunday and so far the truck hasn’t had any issues. Even shifts better. Thanks bdsankey for the parts :thumb:

Anytime!