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Discussion Starter · #1 ·
Hey all . I’ve got a 05 tb stuck in 4 auto . When trying to shift to 2hi I can hear the encoder motor , but not the front actuator . I recently had to replace rack and pinion lines so truck was on jacks for a couple weeks waiting on parts , and once I got the parts and fixed it and went to fire the truck up after bleeding the system , the 4wd service light was lit . Truck was originally in 2 hi and would not shift , but after An hour road trip some how the knob went to 4 auto and it shifted . Now it will not shift from 4 auto . I have pulled the front actuator and has seen it move while trying to shift into 2hi as well as heard a hum from the encoder motor. There is some play in the passenger side cv axle , could the disconnect not working right illuminate a a service 4wd light ? I have tried to pull fuse 8 but it only disengaged the atc and but I can also hear the front actuator let go . I have check all wiring all seems to be intact and good, and I have red almost all forums on these issues and am still stump . Any help will be greatly appreciated right now I have the T case unplugged so the 4 auto won’t engauge as I live down gravel roads . Thanks
 

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'05 Chevy TB EXT
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I wish this wasn't a single paragraph --- again --- but I broke it down in WORD so I could read it ....

If the axle disconnect was actually released, it would allow the axle and CV and tire on the right side to turn 360° --- so you don't have that situation in your descriptions.

You've gotta explain this part: "some how the knob went to 4 auto "

.... did someone reach over and move it or did it do it by itself?

Going on somewhat informed speculation, I'm leaning toward the clutchpack has gone metal-to-metal or the pressure fork/bearing has either failed or gone "over stroked" and cannot return.

It might just be a giant co-ink-y-dink too --- or maybe your turn in the barrel. If you know you didn't accidentally insult a witch at any time in the past year or so, then you can rest assured that someone something isn't picking on you.

I think --- if you haven't ever done it --- this might be a good time to drain that transfer case and see if there's anything awry in it --- like black slime, ****** of metal or needle bearings.

Do you ever drive in the Auto4WD position? If so, this has become the causative agency that could have created this condition. It's never good to use that Soccer-Mom Auto4WD position --- unless, of course, you ARE a soccer mom and have a rich Daddy Gotz Bux.
 

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Discussion Starter · #3 ·
I was at a rodeo and the wife and her friend were drinking around the truck . I then went to leave the rodeo and realized the knob was moved to 4 auto from 2hi . She has no idea how it could have happen so obviously the knob was moved by human to 4auto . Previously it would not shift from 2 hi before I took a 1 hour road trip .
I have checked the tcase fluid and it’s a nice blue and fresh looking . The truck was driven in 4 auto this past winter but not abused as maybe 2000 km was put on over 5 months .

so what originally happend was I had a extensive power steering leak from the rack and pinion lines that run from passenger side of the rack to just below the rack and pinion union for the steering boot .
I was waiting on parts so the truck ended up sitting on jacks for about 2 weeks . ( front end on jacks rear on ground ) . After fixing the line and bleeding the air from my power steering system , I engaged the engine. One the engine fired up the service 4wd light illuminated.
after illuminating, the truck would not shift from 2hi to any other position on the t case .
After a 1 hour road trip someone shifted the knob for the tcase and it moved from 2hi to 4 auto .
Now I brought the truck back from the rodeo in 4 auto and since then the truck will not move from 4 auto . I do not know how to engauge the disconnect as I cannot react the rear wheels spinning while in a parked position to get the disconnect to engauge .
I have unplugged my t case and I can hear it releasing from 4 auto as well as the front differential actuator releasing also . When I plug it back in , and switch the knob to 2 hi it flashes 24 times then stays in 4 auto and the 4wd service light illuminates again.
i have 0 way of getting the truck into 4 hi to verify the disconnect is engaging or not .
Hope this helps
 

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Discussion Starter · #4 ·
Is it possible for the front axle disconnect to illuminate a 4wd service light ? It’s not blinking but On steady
Also is the actuator suppose to create a noise going from 4 wheel auto to 2 wheel high? Because when I try to shift my tcase from 4 auto to 2 hi I hear nothing from the actuator . Only from the encoder motor
 

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'05 Chevy TB EXT
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Let me get this straight --- no bad reflection on you --- OK?

Do you HEAR the transfer case actuator or not?

is the actuator suppose to create a noise going from 4 wheel auto to 2 wheel high?
Yes --- it should go "klunk" when it moves.

I think you've got the "transfer case encoder motor" separate from the "transfer case actuator" and they are the same. It's semantics at best.

Now --- this is intriguing:
"Is it possible for the front axle disconnect to illuminate a 4wd service light ? It’s not blinking but On steady "
YES --- if the front axle slider doesn't move as expected/ordered --- it can make the 4WD Service Light stay ON ... after all, it is part of the system.

Every part has to work as ordered and signify that it is meeting the command; if not --- lights come on.

In other words: Every part of this system that is electrically controlled, also has a "report back" information line back to the computer saying that it worked as designed.

For the record ---
I'm still leaning on the clutches are worn out, the throw-in (is that the correct term?) fork is over-stroked and the throw-in fork (again - is that a correct name? It certainly describes it's operation) has travelled too far and cannot get back to "home" again ---
--- which would allow the clutches to release and the fork/bearing thingy to return to a non-applied condition.​
► That would take the transfer case back to a 2WD position.​

Here's a sinister thought ---- if you had started this vehicle with the front wheels off the ground and the rears on the ground and it was in A4WD or even 4WD High or Low --- this story might not have such a happy ending.

Not that having a messed up transfer case is good news, but that nobody got killed.

I hope I haven't muddied up the water here --- ok?
 

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Discussion Starter · #6 · (Edited)
No you havnt. I sincerely appreciate all the info here . I was talking about the actuator on the front axle disconnect .

The encoder motor makes a hum/whine noise from under the drivers side when I try to switch into 2hi with the key in the run position but engine off .

So your leaning on the front axle disconnect
Or the transfer case ? The transfer case was working 100% perfect fine before I had it jacked up

Also can a bad front axle disconnect cause some serious inner tire wear if it’s not releasing also ?
 

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Discussion Starter · #7 ·
So I just pulled the fuse #8 and I hear a high pitched sound from the transfer case and the front diff actuator .

The driveshaft in the front now turns freely. I’m not sure if that helps with see if the clutches will release or not .

When I put the fuse back in I hear sounds again from under the truck , but the selector again will not switch into 2hi and the drive shaft is locked up solid again .

I have a replacement selector switch here and that is not the issue as I have changed the switch .

The vehicle drives like it’s in 2 wheel drive , no resistance in turns or reversing .

Hope this helps
 

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'05 Chevy TB EXT
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I suspect that the axle disconnect is working as it should ... and the failure is in the transfer case actuator ... but it MIGHT be trying to comply, however the innards are past their use-by date.

That it happened when it did is almost inconsequential ... it happened ... so I'll give that a pass at this time. I wouldn't read too much into this failure other than the fact that .......
A) you recognize there is a problem​
B) the problem appears to be in something associated with the transfer case - be it the controlling motor or the things it controls.​
C) it happened​

The "things it controls" are mostly internal of the transfer case itself ... with just a minute* few exceptions.
(* "minute" is not the time-type minute, but the tiny-type mi•nū_tə)
I think at this point we can dismiss the axle connect-slash-disconnect.
 

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Discussion Starter · #9 ·
Alright so a new update .

I have removed the encoder motor from the transfer case , and tried to move the control shaft on the transfer case. The control shaft moved about 1/4 inch each way . Does that seem correct ? It moves easily but not a whole turn or anything

I have cycled the switch and have seen that the encoder motor did not rotate at all .

I then brought out the ohm meter , with my meter set to 200ohm I tested the yellow and red wires . The ohms meter read 19.5 ohms which tells me it’s higher then normal so something is going on inside the motor .
 

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If the motor is off, in your hand and not attached to the transfer case ... and I'm 'way out of my job description here ... and you try to activate it ... I'm not sure if it's properly grounded.

Anyone who wants to can correct me here .... please do.
 

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Discussion Starter · #11 ·
I sincerely appreciate the information and the assistance with diagnostics here . It was my last resort and sure enough it didn’t let me down !

Thanks a ton for the help ,
 

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Discussion Starter · #14 ·
Encoder motor was the issue .

After further investigation and intensive reading I was able to test the motor via ohm meter.

Normal motor resistance should be around 2-2.5 ohms and mine is sitting at 19.5.

Then motor makes a sound but something jammed up inside not allowing it to rotate .

Like the gentleman said prior to this I will be draining fluid and removing the transfer case also , so I can further inspect internally of the case
 
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