Ok guys I figured out my starting problem and now a week later I have a service 4wd light on. When this happens my 2wd light goes out. And it doesn't seem like I have any control of any of the other buttons but if I turn the truck off for a few minutes everythings works like it should. This happens intermentily while normal street driving in 2wd. Anyone have any ideas. Thanks in advance

 

So I'll assume you have the electronic 4wd transfer case (push button, not a separate stick in the floor). I would check the fluid in your transfer case. Do you put the vehicle in 4wd at least once a month, if you're not using it? If not, you should, to keep all the parts lubed up. Could also be the fluid in your front differential. I'd start there. If that doesn't fix it, it may be electrically related. Let us know what you find.

 

Yeah its the electronic setup. No I usually never have it in 4wd. How do you check the flud in the transfer case? Is it the same as the front diff pull a plug and see if the fluid level is at the bootom of the hole? As far as the transfercase what oil shoud I use I probably should go ahead and change out the fluids anyway. Thanks for the help.

 

unless they have changed things the transfer case uses ATF, thats what the early to mid 90's models used anyway.

I should check mine, thanks for the reminder!

 

FFB, I dont' know. I haven't been under my silverado yet (1 month old) but my old jeep had a NVG 231 transfer case and my silverado has the NVG246 case. Probably similar, but heavier duty. There should be a drain and fill plug on the back of the case (facing the rear axle). If you've never changed it, I wouldn't bother checking, but rather just replace the fluid. Yes, it should be ATF but check a manual (Haynes or Chilton is suffice).

Your differentials use gear oil. Usually something like a 75w-90, real heavy weight gear oil. Again, check a manual. I wonder if these new silverados have a transfer case oil sensor like the engine oil change sensor? That might be your light. Hopefully. Good luck with that!

 

good ol google

http://gm-trucks.com/home/content/view/148/25/

geuss they changed it, go figure.

 

What are you people talking about checking the transfer case fluid. The computer doesn't know if it's low on fluid or if their is even fluid in their so that's not going to affect anything electrically.

But since you mentioned yes they did change the fluid types. It's actually pretty cool cause as it starts to get dirty it will actually change colors to let you know.

As far as your problem though I'm not sure because I'm not there at the truck. It could be as simple as having to update the PCM or their could be a fault switch or something like that. Hard to tell without plugging up a Tech. 2 to pull the codes.

You could try autozone/advance autoparts and see if their scanners will pull the codes but I highly doubt they will. You best bet is to take it to the dealership and see what they find.

 

Your problem is common and easy to fix. You simply need a new 4wd selector switch on the dash doard. This will cost about 55-60 dollars and take about 5 mins. to fix. Simply unplug old one and plug in new. I had the same problem along with several other people I know and this fixed it right up.

 

Can this part be bought at an auto parts store or the dealership.

I looked at mine today and was wondering if you have to remove the dash board to get it out? It took me 5 minutes just trying to figure that out.

Bernard

 

I have a 2005 Z71 and I am having some of the same trouble.My service 4wd light came on and could not take out of 4wd.Brought to dealer (under warranty) they changed out switch and updated a program.Still having trouble but now goes into 4wd sometimes when it wants,they changed out the servo motor and switch this round. Still having trouble when start truck goes into 4wd sometimes and not by me pressing any buttons, no light or code or message.Thanks in advance