No 4X4 auto or manual and ABS light on constantly

[cgamla]

This is on an 02 4.0. The truck will not engage in 4X4 mode at all either with spinning rear wheels in sand or with the manual engage button. The ABS light comes on as soon as the truck rolls about 15 feet.
I could understand that with the ABS issue I would get no 4X4 auto engagement but I don't understand why I cannot manually engage it. The 4X4 light works when the vehicle is started but it does not flash or anything when I press the 4X4 button to actually engage it.
I imagine I have a speed sensor gone bad. Is there anyway to extract a code manually from the ABS system?
I did read about the Brown wire mod that locks out the 4x4 system but wondered if there was a mod available that does the opposite. A wire that would engage the 4x4 on demand and bypass the computer stuff.
Boy I miss my Wrangler with the big lever I just yanked on.
Any help would be appreciated. Chad

 

[rrgone]

Sounds to me like you have two things going on. I think the 4X4 Control Module is dead which prevents it from ever engaging 4WD. And I also think you've probably got a bad wheel speed sensor that's causing the ABS to malfuntion and the light to come on.

When the A4WD system is working correctly you don't need a mod to lock it in. You can put it in 4High or 4Low by pressing the corresponding button and it is locked in 4WD until you press the 4Auto button. You do have to be stopped with your foot on the brake to get it to go into 4Low.

Here's a long thread about the faulty 4X4Control Module in the 2002s:
http://www.explorerforum.com/forums/showthread.php?t=163694. Good info there on where to get a new module and how to replace your old one.

I don't know how to figure out which wheel speed sensor is causing your ABS problem without taking it to someone with high end diagnostic equipment. There's only one sensor for the rear and it's mounted on top of the rear differential and easy to get out. The sensors are pretty cheap online, I'd replace the rear one and hope it's the culpret. If not you're only out about $25 I think. Good luck! Let us know what you find out.

 

[2Fish]

When my ABS light was on, I took it to our local brake/exhaust franchise. They red the code (they have very nice diagnostic equipment) for me and pinpointed the problem. They read the codes for $10, much less than the stealership.

 

[rrgone]

When my ABS light was on, I took it to our local brake/exhaust franchise. They red the code (they have very nice diagnostic equipment) for me and pinpointed the problem. They read the codes for $10, much less than the stealership.

Wow, that was a bargain! What did the problem turn out to be with your ABS?

 

[cgamla]

Thanks

Thanks for the link to the 4x4 module info. I will start messing with it in a few days and post what info I find. Thanks again!!!!!!!!