4x4 Not Working

[thenewguy]

I have a 2004 Gmc Envoy SLE and the 4x4 isn't working. I have no service 4x4 light on. Everything seems to work fine but the front tires won't spin. It snowed a couple of days ago here and i tried going up a hill and I coulnt. The front tires just won't work. I switch into a4wd or 4hi or 4low and I hear the right noises. I've heard that it could be the encoder motor? But I'm not sure. Oh maybe I should add that I did get stuck in mud a couple of weeks ago also haha

[EnvoyBoy2004]

If you have no Service 4WD light on and the selector switch lights are correct, and the front drive is not engaging, the front splined disconnect is likely not working. This assembly is known to fail like this because it dries out and binds.

[thenewguy]

Know how much that could cost to fix? And what are some signs that the encoder motor is out?

[EnvoyBoy2004]

Replacing or servicing the splined disconnect is somewhat labor intensive. The replacement part is also expensive ($250+).

The encoder motor has nothing to do with the disconnect, it is on the transfer case and selects the mode of operation. Since there is no Service 4WD light on, the encoder motor and disconnect actuator are probably working correctly.

[thenewguy]

I still haven't fixed the problem, I went to look under today and saw alot of oil in the front axle of the driver side. Also to add, When I was stuck in mud I try putting it in 4low and while doing so i heard a loud crank.

[roshirim]

Originally Posted by thenewguy

I still haven't fixed the problem, I went to look under today and saw alot of oil in the front axle of the driver side. Also to add, When I was stuck in mud I try putting it in 4low and while doing so i heard a loud crank.

this can be the seal on the front differential.
part # 1925-7296 (seal)
19257296 (which replaced 12471618)
https://forums.trailvoy.com/showthread.php?t=125538

You can make a manual test and see is the front axle disconnect is working.

put the truck in 2WD, remove the 4*4 switch actuator, and push where the hole is located (when you remove the switch actuator) and try to move the front prop shaft. it must be locked.
else try to push a little harder and must lock.. else there is a problem probably with your front splined disconnect axle.

[Jamie1]

do I have to reprogram the tccm when I replace it with new oem part