Allison 5sp: No engagement

[Dmax0389]

This thread pertains to my truck a friend of mine and I are tryin to get to the bottom of this mystery. Manual valve pin along with everything in vb is in place. Starting to believe its either tcm/ecm or ignition switch?

 

[IOWA LLY]

The allison WILL give you 3rd and reverse with NO electric input of any kind. If you have no forward or reverse with the main harness unplugged you have internal problems!! Period!

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[Mpsoldier]

Well sense he's on here I will let him take this thread over lol.

 

[Mike L.]

If he is unplugging the harness and it still won't give him any gears, (should give him 3rd and reverse) I don't care about limp mode or codes. He has a mechanical issue inside the trans. And since we know the pump is drawing and pumping fluid we can rule out a few things.

Best way to diagnose anything is start with the basics. No need to diagnose the electrical side of things until the trans will at least give him 3rd and reverse through hydraulic default.

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Wrong. disconnecting main harness is anot a fool proof that you don't have an electrical problem. Go look at a wire diagram and you will see.

 

[JoshH]

Mike, I don't think he's saying it means there is no electrical problem. I think what he's saying is regardless of any electrical problem, there should be reverse and 3rd if you unplug the harness at the back of the trans. If it doesn't, there is something mechanically wrong in the transmission. Is that not correct?

 

[Evan@InglewoodTrans]

If he is unplugging the harness and it still won't give him any gears, (should give him 3rd and reverse) I don't care about limp mode or codes. He has a mechanical issue inside the trans. And since we know the pump is drawing and pumping fluid we can rule out a few things.

Best way to diagnose anything is start with the basics. No need to diagnose the electrical side of things until the trans will at least give him 3rd and reverse through hydraulic default.

Sent from my SCH-I535 using Tapatalk 2

...

 

[Dmax0389]

Well I haven't had any previous problems with ecm/ tcm or
Ignition switch etc. I agree I should have reverse and 3rd. I'm thinking my next step is diagnosing with tech2..

 

[IOWA LLY]

Mike, I don't think he's saying it means there is no electrical problem. I think what he's saying is regardless of any electrical problem, there should be reverse and 3rd if you unplug the harness at the back of the trans. If it doesn't, there is something mechanically wrong in the transmission. Is that not correct?

That's exactly what I meant. Thanks for clearing that up Josh.



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[the.kiaotee]

The allison WILL give you 3rd and reverse with NO electric input of any kind. If you have no forward or reverse with the main harness unplugged you have internal problems!! Period!

Sent from my SCH-I535 using Tapatalk 2

thanks the 2007 2500 hd is locked up

 

[the.kiaotee]

have to go get under truk now to unplug it

 

[the.kiaotee]

Wrong. disconnecting main harness is anot a fool proof that you don't have an electrical problem. Go look at a wire diagram and you will see.

i dont have a diagram yet

 

[jc1843]

What is the pump pressure at the port-??

 

[Mpsoldier]

what port are you talking about?

 

[IOWA LLY]

The port on the bottom of the bellhousing right beside the spin on filter. It is a tap into mainline pressure. You said earlier you removed that, started truck and fluid gushed out. Is that correct?

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[meshanic]

Have you tried spinning the driveline by hand? A guy once brought me one he had assembled himself. In neutral if I grabbed the driveline I couldn't spin the shaft. He had clutches misaligned & binding up. When you put the extension housing or rear cover on the trans did it go together easy?

I only know the things I have seen myself.

 

[Mpsoldier]

The port on the bottom of the bellhousing right beside the spin on filter. It is a tap into mainline pressure. You said earlier you removed that, started truck and fluid gushed out. Is that correct?

Sent from my SCH-I535 using Tapatalk 2

That is correct btw the guy that has the one post it's his truck obvious dont check the forum to see any updates but all my info I get is from him txting it to me

 

[Mpsoldier]

Have you tried spinning the driveline by hand? A guy once brought me one he had assembled himself. In neutral if I grabbed the driveline I couldn't spin the shaft. He had clutches misaligned & binding up. When you put the extension housing or rear cover on the trans did it go together easy?

I only know the things I have seen myself.

Everything went to gether smooth and we where able to roll the truck in and out of the garage in neutral

 

[Dmax0389]

I currently have truck dropped off to a shop to run diagnose check. I will keep you posted as to what it comes out to.

 

[Robby Avery]

Update?

 

[Mpsoldier]

nothing yet