06Sierra2

regardless of whether it throws a code or not, have u drained the front and rear diffs? in my opinion if you havent you are way past due.

camochevy21

hmm. That's a thought. My 4wd works great, had it on a farm road this weekend and everything is working like a top.

I have not. I bought the truck with 95,000 on it so I don't know if they did before me. . . but it certainly wouldn't hurt. That was on my list of stuff to do.

What is the best brand of fluid to use?

camochevy21

My latest update. So my truck was acting really goofy for a few days. I got it home and the lights were not lighting up on the switch, and it would be in 2 and 4L would be lit up. I used my 4wd this last weekend and everything has been fine since, no light "knock on wood". I think I am going to do as 06Sierra says and go ahead and change the fluids in it.

If anyone has a link on changing front and rear diff fluid post it up, I'm sure I can do it but it has been a long time and it was on an obs so a little refresher couldn't hurt. Thanks for all of your help!!!

Bigredmariner

iTrader: (6)

Changing the fluids is a good idea but the problem you are having is most likely the encoder motor sensor. I just replaced mine a month or so ago, it was doing the same thing that has been described here by others. Front diff has a drain plug so it's pretty straight forward. Rear diff you have to pull the cover off so you'll need to pick up a gasket before hand. Rear will take about 3 quarts and I don't remember for sure the amount for the front. It's a little less than the rear.

camochevy21

10 4. Thank you sir! Any specific brand of fluid you use? Do we have to use Mobil synthetic?