Transfer case motor issue?

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Wylie_Tahoe

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03 Tahoe Z71

Anyone had an issue with what seems like a transfer case shift motor being weak and moving on its own, resulting in a partial 4wd engagement or neutral? Had a case where I had no reverse ( i know, sounds like trans), then some some weird vibrations/noise another time. Turning into my parking spot this AM, the truck jerked like 4WD was on or the rear diff dried to lock up.

With the rear wheels jacked up, runs normal forward, but lots of clanking and jerking from transfer case in revers. Front prop shaft was turning. I could stop it by hand, but it took some effort.

IIRC, the shift motor is not splined but slotted, so it not likes its off a tooth.

TIA,
 
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Wylie_Tahoe

Wylie_Tahoe

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Well, something is for sure, bound up now. Guess im going to have to split the transfer case from the transmission to see if its in the transfer case or transmission. Just wont be happening for a couple weeks though.
 

Fless

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Which TC do you have? There's an RPO code for it in the glovebox, should be something like NPx.

And yes, the TC motors get weak. I had one on my '04 that would appear to switch to 4wd but, in fact, it was in AUTO. Only the Tech 2 would show the correct selection. Bad grounds can also affect how the front diff engages, if you have the AUTO NP8.
 
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Wylie_Tahoe

Wylie_Tahoe

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Ok, i ended up pulling the TC yesterday afternoon. Figured I would, since the truck was broke down at the shop, I had no ride home till later :rolleyes:

After getting the case down, with the trans in neutral, I can rotate the transmission output shaft in the forward direction, but some quite a bit of tension, but cannot rotate it in the reverse direction.

So I think the trans has suffered a major mechanical (hard part) failure.

With the drive shaft plugged back into the output of the TC, it rotates perfectly smooth and quite. Input rotates. Front output turns a little, but I tan hold it, so seems just like a little residual friction. I plan to pull the shift motor off, and manually shift if retest.

I also plan to drop the trans pan and check further, but feel the issue is the trans. But will not rule out an issue with the TC shift motor.

May also crack the TC case apart just for a look. If nothing wrong, its an hour time and a gasket just to see.

@Fless, ill check the RPO's in the AM.
 

rockola1971

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Tranny fluid burnt? Been drag racing it? Tow alot? In OD? Sounds like reverse clutches are burnt and steels are cupping like a frisbee.
 
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Wylie_Tahoe

Wylie_Tahoe

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Trans fluid color and smell were normal. Drag racing? Not since I got. Tow alot? Its a mileage rig, and I got it 5 months ago. I do know a single mom with a bunch of kids owned it the past 2 years.

Trans is indeed toast. Pulled the pan. IMG_20190927_105937015.jpg
 

JonnyTahoe

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Sounds like what mine was doing. Inside of pan had some sludge on the magnet and in the bottom of the pan and one needle bearing but that's all.
 
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Wylie_Tahoe

Wylie_Tahoe

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Mine was tight, but broke loose. I would suggest using a quality 6 point socket. The head is shallow and seems soft. Mine was somewhat rounded from previous removals.

T/C RPO is NP8. Based on the chunks in the pan, I will likely not crack the transfer case. but I will still suspect the motor as being weak, but not likely the root cause of the trans.
 

JonnyTahoe

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Well, something is for sure, bound up now. Guess im going to have to split the transfer case from the transmission to see if its in the transfer case or transmission. Just wont be happening for a couple weeks though.
Mine was doing exactly what you have explained. Removed the T-Case seems fine. was not able to even coast down the driveway in neutral without it binding and jerking. Would Jam-up as I tried to move it into the garage. 295,000 mi. More info coming soon.
 

JonnyTahoe

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Well, something is for sure, bound up now. Guess im going to have to split the transfer case from the transmission to see if its in the transfer case or transmission. Just wont be happening for a couple weeks though.
 
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