SUV erroneously engages 4X4

Hi,

Couple questions. First and most important is you said this is an Auto 4WD system. Meaning it is in 2WD except when the vehicle determines it needs to go into 4WD, correct? Basically, you don't have a shifter that says 2WD, 4HI, 4LO? You have Auto, and then various other 4WD settings?

If this is the case then we could have a speed sensor issue or other sensor issue that is telling it to engage 4WD when it should not. Next have you replaced one, two, or three tires at a time? Meaning if you have an auto 4WD system you need to replace all 4 at the same time. If you don't then the speed sensors will read differently and cause the modules to think one tire is slipping when it is not and it engages the AWD system to keep traction.

Let me know and we can go from there. Thanks

It's not actually slipping in the conventional sense but this is the transfer case. It is the clutches inside the unit that are "slipping" and causing a rubbing or vibrating feeling that may make it feel like it is slipping. This is very common on an AWD vehicle. It is not like this is going to fail all the time but most of the vehicles experience this at some point in its life.

There is a chance that you can prolong the life and calm this down by adding what is called a friction modifier to the transfer case. This is actually made for rear ends because those clutches in the rear need to slip and not grab or you will have a chattering in the rear. However, it works just fine in transfer cases to do the same thing. It will make the clutches slip a little easier and not vibrate. I am just concerned that yours is too far down this path but it won't hurt.

Here is a picture of it from Motorcraft (Ford). It is only a 4 oz bottle and you add the entire thing to the transfer case. Then you need to drive the vehicle for a while so that it works itself into the clutches.

Give it at least 100 miles before you decide if it worked or not.