Hi all,

I'm new to the forum, and I have a 00 Expedition 4x4 with the auto 4x4 (no 2hi setting).

I was had a strange vibration in the front end that seems to be attributed to the automatic 4x4 kicking in. I removed the fuse for the transfer case motor so that it couldn't go into 4x4. This seems to have taken care of the shake. I'd obviously like to use 4x4 at some point in the future, and I'd like to get some opinions on where to start looking.

I just got the truck a couple months ago, two if the tires were shot so I bought two new ones. Now the ones in the front hat 9/32 rears have 12/32. I know this would make the front driveshaft a tiny bit slower than the rear, but would this really be enough to make the 4x4 think it should kick in? I drove a good 500 miles with the new tires before this was a problem.

How can I tell if I need a speed sensor? The speedo works perfect, so I don't think it's that sensor, but there has to be at least one more on the vehicle...how do I know if it's bad?

thanks in advance for any advice.

 

Absolutely it will cause the A4WD to kick in. If you want to test this, swap the front and rear tire ON ONE SIDE ONLY and go for a drive. If the problem is gone, then the issue is with the tires.

 

Thanks for the reply. Do you know if there is an easy way to disable a4wd but leave 4hi functional? I have a feeling my wife won't want to take the fuse in and out. Thanks

 

If this is an AWD you must have the same tire size and even tread design on front and rear. Especially with a AWD...the all wheel drive only works when the computer senses wheel slippage like on rain or snow...just think of the old lady who has a all wheel drive mini van.LOL....but you have a gear ratio in the front and the back and both wheels need to work together...kinda like you wear a sneaker on one foot and a real tight high heel on the other..now walk for a mile....it don't work well...get the same size tires on it...also wrong size tires will throw you speedometer off which than throws off all other computer settings..hope you didn't screw up a transfer case...

 

The tire sizes should be 3/16 off unless manufacturers make the same size tires slightly different sizes. All four are stock size tires, but two of the tires have 3/32 worn off of them. With that said, I understand that it might be enough to kick the a4wd in. Unless I hear another explanation, I'll plan on leaving the fuse out till I have time to get two tires next weekend. This isn't my daily driver. Thanks

 

But of course!

Follow this thread: https://www.ford-trucks.com/forums/1...navigator.html

 

Alloro, thank you very much for the link! I just clipped the wire and found a gravel lot to test it on...works great! I thought about wiring a switch in but I realized that I'll never want auto 4x4. I don't like it for the same reason that I don't like automatic transmissions, the car always thinks it's smarter than I am.

 

Perhaps you should listen to the car , because the reason for cutting the wire is to install a switch. Cutting the wire is the equivalent of removing the fuse. With the wire cut, no power can reach the front clutch which means your 4WD will not work. I suggest you install a switch so that your wife can flip it on along with turning the selector switch if she needs the 4WD.

 

I wonder if it's a little different between years and configurations. From what I read (I went through 10 threads or so), the brown wire goes to the magnetic clutch which only comes into play in A4WD mode and the mechanical clutch is what kicks it into 4HI. I noticed that the thread that you pointed me at does not mention doing it without the switch, but others do.

Brown Wire Mod - Ford Expedition Forum

4HI still works for sure, I tried it in the gravel when I was testing 2WD.

Just for clarification, my Expedition is not an AWD model like (i think) the Navigators are. Mine has A4WD, 4HI, 4LO.

The wire I cut was dark brown, and all by itself coming out of the wiring harness to once side of the transfer case.

Thanks again.