4x4 Problem - Partially Disengaged

[Cailen]

1995 Chev Blazer 4.3 Vortec Vin W with 3 button 4x4

I popped it in to 4hi because of the ice and when I went to put it back in 2hi the hubs wouldn't fully disengage.

This happened a while back and I discovered that my transfer case was overfilled by more than a quart. After the excess fluid was removed the hubs were able to shift once again, but something funky was going on with the lights: the 4hi light would flash briefly when I started the vehicle even though I had left the truck in 2hi, then the 2hi light would come on. Unfortunately I just haven't had time to fix the REAL problem, but I have some time this weekend.

I drained the fluid when I got the truck home and sure enough about a half a quart came out of the fill plug.

I read in some threads I searched up that there is some sort of "pin 13 test", but I failed to find anything other than mention of this test.

[Cailen]

Update: leaving the negative battery cable off over night allowed me to shift back in to 2hi thismorning. This suggests that it is in fact the encoder motor, correct? What causes this problem? Is there a GM service bulletin available?

[MT-2500]

233/244 transfer case.
Jumper pin 13 to ground turn key on and read codes by counting flashes on 4W indicater light.
Post back codes.
If transfer case is overfull check main trans fluid level.
Fluid may be going from main trans back to transfer case threw the seperator seals.
MT-2500

[Cailen]

Thanks, I'll do this tonight. The seal was suggested when I first encountered the problem. Is this the seal that separates the transfer case from the transmission? When the Tcase fluid was 1L overfull trans fluid level was good. My hope at that point was that it was just someone who had serviced the Tcase and pumped the fluid in and quickly popped the cap on.

[MT-2500]

There is twin seals that seperate them.
Drain the transfer case down to full and keep a eye on it.
Post back what code you get.
MT-2500

[Cailen]

No code (flashed once, 3 second pause, flashed once.....).

I checked transmission fluid level today after work (and yes, I made sure to use the proper procedure) and I was over a quart low. Tried shifting in to 4hi, shifted fine again. Tried shifting back to 2hi and blew the fuse again. Brought it home, shut her off, replaced the fuse and it shifted to 2hi.

[MT-2500]

Well that expains why the transfer case was over full.
Keep, a eye on it for a while may be just a slow leak from traans to transfer case.
Also you have a code 1 on transfer case.
But clear the code and make sure it comes back on with the fuse good. Before replacing anwthing.
Here is a link to the test for code 1.
http://members.troublecodes.net/crunch/code1.pdf
MT-2500

[Cailen]

Well that was a bit silly.. I suppose I should have replaced the burnt fuse before I did the test.

I'm not going to jump the gun and start replacing parts left and right, but would you happen to know the GM part number for that encoder motor? I'd like to price it out.

[MT-2500]

You need to call your dealer and have your vin no handy for a price on part no.
Try to test it with a good fuse.
Not sure on what is knocking out the fuse.
Good Luck MT-2500

[Cailen]

Fuse goes out whenever the hubs partially disengage from 4hi to 2hi. Resetting the encoder motor seems to be the fix, but I'm not positive it's the problem. Any further steps I can take to try and diagnose the problem?

[MT-2500]

Looking at the wiring it could be the transfer case control module or the transfer case motor.
The fuse feeds the module and the module feeds power to motor
If you have a amp meter you might do some test on the shift motor amp draw.
The module reverses power to run the motor back an forth.
Other than that I can not find much info on testing for short.
A chev dealer tech may have some info or ideas on it.
Good Luck and let us know how it goes.
MT-2500

[shell706]

I have a similar problem. When i put my truck into 4hi it will work for a little while and then I will hear a clunking noise. It sounds like the 4x4 is disengaging and then reengaging. If someone could help me out that would be great.