Allison 5sp: Nightmare in Idaho, Built 5spd killing Transfer Cases

[raceghost]

If it continues rotating then it is a mechanical issue. If it stops then it is a TCM issue

I guess I never asked what it should do if things are acting correctly?

Don't have any answers yet. Been told there is movement with it throwing a code P0847, and that they have replaced some electronics within the transmission and things are acting correctly...

Though they never ran the test we are discussing in question. I still would like them to run the test in question, though I am not sure of results we should see if things are in fact fixed or still have a hidden issue....

 

[Burn Down]

If you pulled the plug on the back of the trans wouldn’t that rule out the tcm.

x2, this should be a very easy diagnostic for the shops. The Allison has a (very basic) hydraulic failsafe mode when the rear connector is unplugged.

If it continues rotating then it is a mechanical issue. If it stops then it is a TCM issue

.....

 

[raceghost]

Burn Down,

Yes, I understand exactly what you quoted, though that is if you need to do the test, to identify an issue. What should happen if there was no issue, but you still decided to do the test? What should happen if things are working correctly? What would be concidered normal?

 

[gmduramax]

Trans goes into a mechanical fail safe. I think it’s 4th and reverse that works only. If your tcm was infact the problem. It should go away after unplugging the harness.

 

[SmokeShow]

If you unplug it and things work properly (shaft stops turning while in Park), it won't still turn the input shaft. So if the shaft stops turning after unplugging the TCM, the TCM was trying to command it. Not likely to be the case. If they unplugged it while the shaft was still trying to turn in spite of being in park, then it's a mechanical issue making it still pull. This is the likely case.

If it is fixed now by whatever they did, that means the shaft isn't spinning while in park so it should stay that way if you disconnected the TCM. Then it would default to only having 4th or Reverse when shifted into gear with the TCM disconnected.

 

[raceghost]

Trans goes into a mechanical fail safe. I think it’s 4th and reverse that works only. If your tcm was infact the problem. It should go away after unplugging the harness.

If you unplug it and things work properly (shaft stops turning while in Park), it won't still turn the input shaft. So if the shaft stops turning after unplugging the TCM, the TCM was trying to command it. Not likely to be the case. If they unplugged it while the shaft was still trying to turn in spite of being in park, then it's a mechanical issue making it still pull. This is the likely case.

If it is fixed now by whatever they did, that means the shaft isn't spinning while in park so it should stay that way if you disconnected the TCM. Then it would default to only having 4th or Reverse when shifted into gear with the TCM disconnected.

Thanks guys for clarity.

They say it is fixed with this excerpt from an email:
"THE TRANSMISSION INTERNAL ELECTRONICS CHANGED WERE, THE PCS(D),PRESSURE MANIFOLD SW,& INTERNAL HARNESS ASSEMBLY. THERE IS ALSO A NEW MLPS IN PLACE WHICH WE CHANGED EARLIER (A KNOWN PROBLEM/ISSUE ON THIS PLATFORM). I DO RECOMMEND LEAVING IT IN PLACE AS EVERYTHING IS WORKING WITHOUT ISSUES AT THIS TIME."

I have an email stating 2 weeks ago that the MLPS made no changes to issues with 2nd transmission, though in quote above, they say it did...

I asked them to run this test we are discussing anyways, just to make sure we have no hidden issues, but they are reluctant to at this time, since they have put roughly 100 miles on this transmission after quoted fix above, and testing 4hi and 4lo shifting with no issues, and want me to come get the truck...

 

[2004LB7]

So, by them changing some parts inside the transmission and it correcting the issue they are admitting fault

They should refund you all expenses for the t-cases and diagnosis both with them and the dealership

 

[Mike L.]

So, by them changing some parts inside the transmission and it correcting the issue they are admitting fault

They should refund you all expenses for the t-cases and diagnosis both with them and the dealership

Bet it doesn't happen. Total mis-diagnosis. With all that has been changed, we will never know.

 

[Ne-max]

You said 2 complete road rippers from Omaha got shipped there. Still had issues. Seems fishy to me cause those are drop in ready units. I think the location is screwing you. Have you tried reaching out to corporate?

 

[2004LB7]

Bet it doesn't happen. Total mis-diagnosis. With all that has been changed, we will never know.

Yeah, it is probably to far fetched to assume it would happen