After using the truck's in 4x4, I noticed agrowling noise coming from the front end when i returned to 2x4. I may have a bearing going bad, or the truck may be partially stuck in 4x4. It is not in full time 4x4, but it may be in auto 4x4. The 2x4 light is on.

How exactly does the Auto 4x4 work? I thought it engages the trasfer case, and when slip is detected it engages the front diff. Is this correct.

When the truck is moving in 2x4 the front driveshaft is turning. Is this correct? This leads me to believe it is still in auto 4x4.

I'm trying to avoid taking the truck back to the dealer?

Truck only has 75k miles

 

i cant help muchbut, i know that if your front wheels are turning your drive shaft will also turn,whether its in 4wd or not.

 

My truck does the same thing, but from auto4x4 to 2x4. I usually just tap the gas pedal a few times and after a minute it goes away.. If its still doing it in 2x4 for a long timethats a problem, but if it goes away after a few miles id just leave it alone. Im not too experienced in the 4x4components so wait for a more experienced guy to help you.

 

I don't have the auto 4x4 but I know a little about it, If you are in 2 wheel then it "should" unlock the drive line and it will spin free. That is what is sapposed to happen with these newer trucks. I have experienced that if when transitioning from 4 wheel to 2 wheel drive you should put the vehicle in reverse after changing the selection due to tension in the drive lines, this should ileviate the factor of it not shifting all the way out of 4x4. Now as far as the front diff locking and unlocking that could be gummed up, due to lack of use. My understanding of how the newer trucks lock in and out in the front diff is an AIR of solinoid acctuator that lockes it in and out when needed. if the air line is cracked, it will not lock. if theactuatoris stuck then it may not lock in and may not want to unlock very easy. Other than that, you would have to talk to someone with a little more knowledge of the actual inner workings of the front diff on that spacific truck. I would try to avoid using the Auto 4x4 for the reason that is waists gas and it is unreliable. I have been told that the 4x4 on these trucks have to roll 1.5 revolutions of the tires to be actually fully locked and ready for torque. I haven't had a problem with my truck locking in but have had prblems with it unlocking when the front tires were different diameter size than the rear. (I had 33's both front and rear, but different brands) That caused a little bit of tension between the front and rear. Thus the reverse thing worked for me.

 

They tend to gum up if not at least put in 4x4 on a regular basis. And I always back up a little after going back to 2x4 to make sure it is free, except in auto 4wd. I only use that on wet or icy roads, and it really works on wet roads that et deep ruts. No more hard yank of the wheel if you don't slow down.

 

I agree with smoke20, you should pop it in and out about once a month or once every other month to keep it "free" and keep the grease where it needs to be. If the front hubs are still vacuum operated (like my 91) then the front drive axle will engage and disengage with the press of the button. The hubs, however, may take longer to engage and disengage as they need the right vacuum pressure (and some movement from the front wheels if the truck is getting old), to disengage. Anywho the rumble is the spinning of the front axle as the hubs are still locked despite the front driveshaft being engaged or disengaged.

 

The newer trucks (with IFS) lock in the differential, not at the hubs. I have already figured that one out! Yes, every month sounds about right, that should also be about how many times at bare minimum that you should be off road and possibly need your 4x4! Just my opinion. I use my truck for work and play.

 

I agree that you shouldHAVE to use your 4wd at least once a month, but unfortunately work disagrees right now. Its funny to see 10 mud trucks at the office, all clean. No one seems to have time right now. What a shame. I might as well go buy a ricer and save on gas.......yeah right, not gonna happen!!

 

I know people that do it, I just laugh at them! Esspecially when there has been so much rain out here lately.

 

when the truck is in 2 wheel drive the 4 wheel drive shaft is not locked in so it will not spin it should be in neutral. there may be something wrong with ur transfer case.