Allison 5sp: Trans Noise?

[S Phinney]

I was testing the waste gate tuning this evening and limped the trans setting a P0790 code. There was a noticeable grinding and no gears. I cleared the code while rolling and had gears again. I idled back into my shop and looked for leaks. I saw one from under front of trans but it was fuel. I think I may have lost a CP3 also. Any ideas?
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[S Phinney]

Nobody have any opinions on the vibration/ grindy kind of noise when rolling?

 

[Mike L.]

Never heard of a P0790 code. Cannot find it.

 

[S Phinney]

Never heard of a P0790 code. Cannot find it.

Its a normal/performance switch error. I'm guessing tow/ haul. I did ha e tow on to lock the convertor.

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[THEFERMANATOR]

Make sure the 2 orange wires that go into the shifter aren't shorting out.

 

[S Phinney]

Make sure the 2 orange wires that go into the shifter aren't shorting out.

That is not the problem. The tranny has to come out. There is no 4 and 5 gears. The hub or planet must be broken.

 

[Mike L.]

Your first post said no gears. That is not the C2 hub or P2 planet. If in fact you twisted the splines, you would still have 1-2-3. You would also have thrown a P0776/777 code if that happened. From doing some research; your p0790 code does not pertain to the 1000 trans. The normal/performance circuit is not activated in our TCMs. It has nothing to do with T/H.

 

[S Phinney]

Your first post said no gears. That is not the C2 hub or P2 planet. If in fact you twisted the splines, you would still have 1-2-3. You would also have thrown a P0776/777 code if that happened. From doing some research; your p0790 code does not pertain to the 1000 trans. The normal/performance circuit is not activated in our TCMs. It has nothing to do with T/H.

I did have no gears until I read and reset. I do have 1-2-3 gears. I did drive the truck for a slow test drive to see if any gears were effected. I do not have 4-5. I did not have any codes other than the one I posted. This occurred at the 4-5 shift at around 100 mph. It hits the rev limits and I stopped read codes while running, reset and idled back into the shop without any shifts. Either way it has to come apart.