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Np 246 Transfer Case

drag230

By drag230
in Ask A GM Technician

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drag230 Enthusiast

drag230

Posted
Posted

I have a 2002 Yukon XL, 3/4ton, 4wd, 8.1 liter, 94,xxx miles, pushbutton switch with auto 4wd. Had the transfer case rebuilt by a reputable garage over a year ago and is now out of warranty. Typical reason, hole in the rear case caused by the pump. When I slow down it seems as though the transfer case goes into neutral. Engine rpm's go to almost idle and I can rev the engines rpm's. It sounds like 2 gears rubbing together and not engaged and does change with engine rpm. It does not sound as bad as when you miss a gear on a 4 speed. If I allow it to coast down to a lower speed it reengages and I can continue on. I tried the encoder motor which appeared to fix it for about 2 months but it has returned now. In another post they replaced the sensor (P/N 88962315) in the encoder motor. I figure since I replace the encoder motor I must have replaced the sensor. They also mention that the wiring harness could be bad. I would very much appreciate any help you may have to offer.

 

Thanks

Drag230

Matt_ Senior Enthusiast

Matt_

Posted
Posted

Sounds more like a trans issue than a tcase issue to me. Especially if it's doing this consistently.

 

If the T-case was was shifting into N randomly you'd be getting at least an encoder sensor fault. Are you getting any faults?

drag230 Enthusiast

drag230

Posted
  • Author
Posted
Sounds more like a trans issue than a tcase issue to me. Especially if it's doing this consistently.

 

If the T-case was was shifting into N randomly you'd be getting at least an encoder sensor fault. Are you getting any faults?

 

Does not do it consistently. No codes at all in any of the computers. It has a 4L80E transmission in it. I have a hard time believing it is bad, besides I don't know anything in the trans that would act like that. Convertor is the connection between the engine and trans and if I heard the sound of gears rubbing together I'm pretty sure the convertor would be done. Any other suggestions.

Matt_ Senior Enthusiast

Matt_

Posted
Posted

I've never heard of a T-case shifting in and out of Neutral like that, but i have heard of transmissions doing what you described. Not saying it's not possible.... just very unlikely IMO.

 

Without driving it for myself and checking the computer for codes, can't really point you in any worthwhile direction other than to bring it to a good trans shop. (Trans shops work on tcases too if that is actually the problem).

drag230 Enthusiast

drag230

Posted
  • Author
Posted
I've never heard of a T-case shifting in and out of Neutral like that, but i have heard of transmissions doing what you described. Not saying it's not possible.... just very unlikely IMO.

 

Without driving it for myself and checking the computer for codes, can't really point you in any worthwhile direction other than to bring it to a good trans shop. (Trans shops work on tcases too if that is actually the problem).

 

Thanks for the info. I haven't ruled out the Trans. I really think it is an electrical issue. If it is mechanical it will continue to get worse and hopefully grenade. Then I'll be able to repair it. For now just trying to eliminate the inexpensive (if there is such a thing) parts. Next is checking switches and connectors on the trans.

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