Allison 5sp: Trans Issue Update

[SSchmi5519]

Just updating on this from the other thread.

I replaced the Pressure Switch Manifold per Mike's recommendation and while I was under there also replaced the NSBU. At 95k miles, I just figured good preventative maintenance.

The trans is still having issues and throwing the P0847 code.

If I clear the code I can drive around in 1st gear with no problems. It will then free rev for a second or so and clunk into 2nd.

When it comes time to downshift, the trans locks up (locks rear wheels up), throws the code, and the truck stops. No longer being able to move forward, only reverse, until the code is cleared.

Now Mike is thinking its a wire that has rubbed through somewhere causing electrical issues with the trans. The wire could be internal or external.


Just throwing this up here for any other ideas and for other to ponder on, etc.

 

[REDHOSS02]

Man I wish I could help somehow...I know how frustrating tranny problems can be seeing how it could be wiring, solenoids, or clutches. Everytime I ask someone they say we'll have to pull the trans and figure it out. I feel you bro!

 

[SSchmi5519]

I'm still on the search for the delinquent wire, or relaxed pin.

 

[IOWA LLY]

How many miles on the build?

 

[SSchmi5519]

15-20k

At this point I have it narrowed down to only a few wires, hopefully it isn't internal and is an easy fix.

I'll post a picture of the area where the wire is grounding, and maybe save others from the same problem in the future.

 

[SSchmi5519]

Update: Did more searching, poking, prodding, plugging, and unplugging today.

Took it for a test drive and it drove normally, returned home, shut off, tried again, and right away popped the P0847 code and the trans locked up again.

I cleared the code and returned home in 1st gear.

 

[Chevy1925]

Ill see what i can do to come down and help this weekend steve. I owe ya beer since you turned 21 anyhow

 

[SSchmi5519]

Yes yes let me know. I got the name of a certain tech at the Allison distributor/repair center down here. He is supposedly their go-to guy for the Alli 1000.

If i get a good feeling that he knows what he is doing i'll have the truck towed to their shop.

 

[Chevy1925]

Yes yes let me know. I got the name of a certain tech at the Allison distributor/repair center down here. He is supposedly their go-to guy for the Alli 1000.

If i get a good feeling that he knows what he is doing i'll have the truck towed to their shop.

good deal bud.

 

[Mike L.]

We might have a sticky D shift valve or wire going to it.

 

[SSchmi5519]

What causes a solenoid to stick? And does replacing the solenoid solve that problem?

I can throw a new solenoid in there a lot easier than towing the thing.

 

[Mike L.]

What causes a solenoid to stick? And does replacing the solenoid solve that problem?

I can throw a new solenoid in there a lot easier than towing the thing.

It is cheap enough to throw in but we don't know if the valve is sticking or the solenoid is good or bad.

 

[SSchmi5519]

Bought a new D solenoid. Do i need to drop the valve body to put this in?

EDIT: If it helps with the diagnosis, the condition seemed to become gradually worse as opposed to happening at once.

 

[Chevy1925]

Mitchell on demand says you dont have to (dont mean they are right though lol), and from the pic they show it looks easy to do. ill text ya steve

 

[SSchmi5519]

Does it say which one is the D valve?

Also Mike, if you read this before I call you, what needs to be done to "clean/polish" the D valve?

 

[hondarider552]

I'll text you too.

 

[SSchmi5519]

By text I hope you mean sext.

 

[hondarider552]

Get cha head outta da gutter!

 

[BLKLMM]

:gay:

 

[paint94979]

Sexting or Twatting?