02 Exp goes INTO 4X4 by itself.

[sro2000x]

2002 Exp 4X4 EB.

Ok, Ive read hundreds of post about this SUV NOT going into 4X4 but my problem is it wont STOP going into 4X4 High on its own.
I have seen others post with this problem but they have been totaly ignored.

This is a different problem.

Automaticly goes into four wheel drive on dry paved roads.
The lights all work fine.
The switches all work fine.
Can be put into 4X4 high or low with a button press.
Can be taken out of 4X4 by pressing 4X4 Auto.
But it will go into 4X4 at random.
Any ideas?

 

[Glen4X4]

Welcome To The Forum!

I would think possibly a faulty sensor on the front wheel making it think the front wheels are not spinning the same speed as the rear.

 

[thepotroast]

It's called Auto 4x4 for a reason.

If you have a light coming up on the dash that's saying 4x4hi...then that's a different story. But if you're referring to feeling the front wheels gripping on pavement...that's what it does. The truck is ALWAYS in 4x4auto unless you manually configure the 4x4 module to disable the front, which is called the "Brown Wire Mod" which can be found on the sticky thread at the top of the Modified 2002-2005 section.

 

[Glen4X4]

He's stating it does this on dry pavement and just doing normal driving it shouldn't be engaging in 4X4 it should only do it if you gun it pulling out of somewhere or on slick surfaces like wet roads, gravel.

 

[thepotroast]

He's stating it does this on dry pavement and just doing normal driving it shouldn't be engaging in 4X4 it should only do it if you gun it pulling out of somewhere or on slick surfaces like wet roads, gravel.

My front end grabs on pavement all the time. It's quite common as the trucks are always in Auto 4x4. The 4x4 module is always "testing" the front wheels to apply grip if needed. This is very apparent anytime you turn the wheels on dry pavement.

A very common occurrence of this takes place with uneven tread wear tires...which is why it's important to properly rotate them in appropriate intervals.

 

[sro2000x]

Glen4x4 you are correct. This is not normal.
It is going into 4x4 on it's own.
Even when NOT moving or going in reverse!

I can put it in 4x4 with a button press but cant always get it out by pressing the auto 4x4 button. Makes me think the sensor is telling it to go into 4x4 high and will not let me override the choice manualy because it thinks there is a speed differance between the front and rear.

I'm leaning towards a bad sensor.
Anyone know how to change them?
I think there are two in the transfer case.
Any thoughts on the case oil being the problem too?
43K miles and never been changed.

 

[thepotroast]

Glen4x4 you are correct. This is not normal.
It is going into 4x4 on it's own.
Even when NOT moving or going in reverse!

I can put it in 4x4 with a button press but cant always get it out by pressing the auto 4x4 button. Makes me think the sensor is telling it to go into 4x4 high and will not let me override the choice manualy because it thinks there is a speed differance between the front and rear.

I'm leaning towards a bad sensor.
Anyone know how to change them?
I think there are two in the transfer case.
Any thoughts on the case oil being the problem too?
43K miles and never been changed.

So again...I ask...is the "4x4 high" light coming on or not?

 

[sro2000x]

yes

 

[Glen4X4]

Oh ok so High is illuminating when the 4X4 suddenly comes on....so now I would point to the module or possibly less likely the switch.

 

[thepotroast]

yes

That helps the diagnosis significantly. See Glen's post above for a solution to your issue. That's why I asked earlier

 

[Glen4X4]

Don't forget for a temporary fix you could do the brown-wire-mod but I would still replace the module because it could develop more problems.

 

[k2sb2003]

check your tires. according to the local ford dealer any thing over 2mm difference between a front and rear wheel will trigger 4x4auto but if auto is constantly having to activate then it will automaticly lock 4x4 high.