'96 XLT 4wd problems

[nism0racer]

Hello everyone! It's my first time posting here but I have been browsing these forums for over 2 years now and I just want to say this is one of the best resources of information on the net. Anyway, I've had my 1996 Explorer XLT for about 4 years now and its been pretty great. The only major problem I had was the tranny rebuild at 100k miles. The OHV motor hold up pretty well (just burns oil a little).

Now to my peculiar problem. I've beat up on my 4wd pretty well, especially when I first bought the truck during the winter season. I was very surprised with its 4wd performance; even if it was just 4wd auto, we never got stuck in the snow. Now, lately I have been having problems. When I switch to 4x4 auto, the lights come on, but if I go to highway speed(around 50mph), the 4x4AUTO and 4x4LOW lights start blinking 6 times. I know these are the speed sensors, but I performed the "anti-brown wire mod" to have the 4x4high feature in the control trac(on-off-on switch) to get around the problem. A few weeks ago I tested out this mod and I experienced binding when I switched it to the 4high feature(12v from cig lighter to clutch) which means its works right?

Now it just snowed 20 inches here in NYC and when I took the explorer out, I was getting very poor performance of the 4wd(4x4 Auto on the main switch and 12v on the brown wire). My rear kept slipping out and I saw no movement of the front wheels. Sometimes, I would hear alot of "thunking" noises when my rears were slipping. Also, sometimes I would feel that there were some power going to the front, but very little, and not enough to cause them to slip. My tires arent very good for snow and theres about a little less than 1/2 of an inch of thread left on the rears. What do you guys think the problem could be? Is it just the tires or a 4x4 engagement problem? Do you think the speed sensors are still affecting the 4x4 even though I did the brown wire mod?

Also does binding automatically means that power is going to the front wheels? Because it did bind when I tested it out a few weeks ago...

Thanks in advance!

 

[SkanlaxJMO]

the 4wd light blinking has been covered several times.....For me it was just pulling the neg. terminal on the battery for 15 minutes and it was all good.

 

[gijoecam]

If you've done the anti-BWM, there's going to be a couple more things to look for. The first is that the ground from the t-case clutch coil isn;t getting back. You can check this very easily: Unplug the t-case and chack for continuity to ground through the brown wire going into the t-case.

Now, assuming that is OK (i.e. you have a ground path) the next thing I would look at is the transfer case. It's simple enough: Put the truck on stands or a floor hoist, engage the 4 auto and BWM switch to lock it in, and drop it into drive. Look to see if the front driveshaft is locked to the rear driveshaft. They should both turn at the same speed. With the truck in park, give the driveshaft a good twist by hand and see if she'll turn. If not, odds are the t-case is probably OK.

From there, you'll want to check the center-axle disconnect on your front axle. If that fails to lock in (and it's more common that we'd like to admit) even though the power is being sent to the front driveshaft, the front axle acts as though you have a broken axle shaft (because essentially you do).

Simple check: With the truck in the air, 4wd locked-in, BWM switch on, front driveshaft should be locked to the rear. Turn one front wheel. The other wheel should turn the OPPOSITE direction. I suspect that yours will not. If one wheel turns but the other doesn't, it's a clear sign that the front axle failed to engage.

Now, what causes it? Vacuum leak, sticky solenoid, or bad CAD. The solenoids are cheap (there is one that engages and one that disengages. Usually one of them sticke, so you get vacuum on BOTH sides or vacuum on NEITHER side of the diaphragm, and nothing moves either way), the vacuum lines are simple enough to trace, and the CAD isn't generally prone to failure, but can get gummed-up and sticky with time. You should never have vacuum on both hoses at the same time, but should always have vacuum on one of them. Sooooo.....

The easiest way to check 'em: With the engine idling in park and the front end in the air, you should have vacuum on the disengage hose. Then, flip the switch to auto, and you should have vacuum on the ENGAGE side. If you get no change in state, one or both of the vacuum solenoids has failed.

Start there and let us know what you find.

-Joe

 

[nism0racer]

thanks alot gijoecam.. Ill be sure to check those out today. I have one more question... im pretty sure I was binding when I last tested it out on dry pavement... doesnt that mean my front was getting power? Thats what kind of stumps me. I'll let you guys know what I find

 

[gijoecam]

If it's binding, then that's usually a good sign that it's getting power and everything is engaged the way it should be. However, I kind of thought from your post that it was only intermittent....

It's also possible that, once the lights start blinking, the system disables the 4wd and unlocks the front end. I can't say for sure. If so, that would also explain the loss of power to the front end as well.

As for the blinking lights, that's commonly caused by a bad speed sensor. That's been discussed on here before. Apparently the design of the early second-gen cases is a little bit different WRT the speed sensors. I'm not too familiar with the guts of the two cases, so I can't help much there.

-Joe