04 Envoy 4x4 lo won't disengage

MLB

Original poster
Member
Aug 7, 2012
4
I have a 2004 Envoy 4x4 in line 6cyl that wouldn't go into 4x4 when I first got it. Finally it went into 4lo but now it will not come out. I have tried it in neutral rolling/stopped both as the manual says. Tried rolling down the street backwards (in neutral). Even tried with front wheels off the ground. No luck.

Transfer case fluid was just changed at 114,000 miles. (not sure of it's history before now. Just purchased the truck). Auto track 2 fluid was used.

I can hear the 2 distinct buzz sounds of the TC encoder motor

I think I remember hearing the front actuator as well before it finally did go into 4lo. Now that it's in 4lo will I not hear it? Remember reading that the front actuator only turns on when switching from 2 wheel to all wheel drive. Is this correct? If this was bad would it keep it stuck in 4 lo?

I have all the proper lights on my knob. When switching from 4lo to any other option, the new option will blink steady for about 5 seconds but then default back to 4lo.

The service 4x4 dash light is NOT lit.

When spinning one front tire the other tire turns the opposite way - but there does seem to be a couple of inches of play before it will engage. Is this normal or is something worn out?

What should I check or replace first? My hunch is the transfer case encoder motor. Would like to narrow it down with more than a hunch.

Thanks for all you help in advance.
MLB
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
It's sometimes the encoder motor, as you figured. Rarely a fuse or the TCCM. Usually it's the owner forgetting to be in NEUTRAL. :redface:

The front axle actuator does not move except in the two transitions 2HI->A4WD and A4WD->2HI, as you understand.

A couple inches of rotation is normal.

You can always pull the encoder motor and rotate the shaft in the transfer case that it moves by hand to see if it's jammed, or if the encoder motor is jammed internally. It's the only way at this point to get it out of 4LO mode to drive it anywhere.
 

MLB

Original poster
Member
Aug 7, 2012
4
thanks for the quick reply roadie.

removed tc encoder motor. it won't turn. but neither will the transfer case. grabbed it with pliers and got it to move clockwise about one click. should it move freely?

Do I need to have all the tires off the ground to turn it?

What's my next move?

btw here is a pretty good article with pics on the subject for anyone looking to understand... as i have been

http://www.offroadtb.com/articles/tech-docs/transfer-case-tech-the-nvg-226-np8-theory-of-operation/
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
That shaft should turn with the tires touching the ground. I don't know how much force it takes. Buying a vehicle with a known problem like that should have gotten you a discount suffiicient to buy a used transfer case if that's what it takes.

How much fluid came out when the TC was serviced?
 

MLB

Original poster
Member
Aug 7, 2012
4
Luckily I purchased this for $2000. I have room to play/pay.
A little less than a quart of fluid came out. Was def low.
Am I correct to assume the transfer case needs replaced/rebuilt if the spline won't turn?
Any idea which direction I should be turning the spline? Clockwise or counter clockwise. It's stuck in 4lo and would like to get to 2hi
 

MLB

Original poster
Member
Aug 7, 2012
4
thanks roadie. i found that link earlier as well. thought i posted it. anyway...

pretty sure my transfer case is shot. it's making some "wonderful" noises.

i think my encoder motor is toast too. it won't turn.
got a link or brand of encoder motor you recommend?

btw, you are not a roadie - you are a rawk star
 

BRomanJr

Member
Dec 9, 2011
371
MLB said:
thanks roadie. i found that link earlier as well. thought i posted it. anyway...

pretty sure my transfer case is shot. it's making some "wonderful" noises.

i think my encoder motor is toast too. it won't turn.
got a link or brand of encoder motor you recommend?

btw, you are not a roadie - you are a rawk star

Encoder motors should not normally turn from the Transfer Case (TC) side, they are geared so low and have an electric Brake so that you should not force it.
Connecting it electrically while not mounted to TC is the way to test it.

The reason they are geared so low is that the effort to turn the TC through some modes is tough, but you should be able to move the TC shaft with some leverage.

Not sure which way to turn though, If the Encoder moves when commanded while unmounted that should show you where to turn the TC shaft.
 

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