I recently posted a question about the 4wd on my uncle's truck. now i have discovered it is not good. I switched it into 4wd high then it switched itself into 4wd low and displayed the same 4wd service warning then i switched it out of 4wd then back to it and when i shifted into drive the transfer case started making a terrible gear grinding noise in 4wd high. I admit i switched it into 4wd when rolling down the road to test it. I wonder if i might have broke it. (its a 2011 f150 twin turbo engine with 119k miles on the Od) Could this be a defect or did i mess it up?
Did you or he ever drive it in 4×4 on a dry road? Did you just drive it on dry roads? I really hope you didn't. That will bind up the driveline and can destroy things in a hurry. 4×4 in a truck doesn't operate the way AWD in a sedan or crossover does. It should never be on when you're driving on dry, paved roads. It will not allow the front and rear axles to rotate at different speeds. Your transfer case rotates the front axle at the exact same speed as the rear at all times, neither end can speed up or slow down relative to the other when they need to. The the only reason they don't destroy themselves off road and in snow and ice is because tires can slip on dirt and snow. Rubber and dry asphalt doesn't allow any slip and can snap gear teeth in the differentials and transfer case.
I drove it in 4x4 on the road because a while back when he had a 2007 f150 the transmission went out on it and the mechanic that fixed it said to use the 4x4 every once in a while to keep it from locking up. I'm not sure if he was telling the truth. And i read about the 4wd on the truck and it said "The 4x4 system can be used (or engaged) at any speed" i'm starting to think that the information panel on the display was lying to me. but i assume that i broke it.
I've engaged the 4×4 on my 1999 Ranger going 25 on a snow covered roads before and it engaged right away. No problems. If you just drove it on a dry surface street and made turns, then you probably destroyed something.
Usually i use common sense but i guess i put to much of my trust into the information on the screen.
Not using 4×4 can cause it to stop working correctly, eventually. I bet the mechanic probably didn't say to only drive straight ahead if you're going to do that on a dry street. About once a month or so I drive my Ranger to my girlfriend's parents' farm, drive back in a field, throw it in 4×4 and do a figure 8 to keep everything moving.
My Ranger won't allow you to put it in 4×4 Low without fully stopping the truck, putting it in neutral, then switching it. I'm surprised the newer F-150 doesn't have that feature.
Just for future reference, 4×4L is meant for situations with high torque needs and very low speed, like driving on muddy inclines. Don't use it on a road, wet or dry. 4×4H is meant for driving on surfaces like a snowy road or grassy field, where high torque isn't needed, regular driving speeds are.
When some guys look to buy used 4×4 trucks, they will put them in 4×4H in a parking lot for just a second, turn the wheel to lock and just creep a little bit. If it's working correctly, the vehicle will jump up and down- that's the driveline binding.
Hopefully you learned something out of your ordeal and your uncle doesn't get angry with you.
To answer one of your questions, yes you should drive in four wheel drive on a regular basis to keep the system working properly. My toyotas usually say 10 miles a month. I admit I may not always do that, but I find a dirt road and take a pleasure drive in 4x4 as often as I can. Also don't forget to change your differential and transfer case fluid.
