4WD issue 1996 Explorer XLT Control Trac

[artray724]

Ok, new here, Hello everyone.
I recently picked up an Explorer to use as a beach truck to go fishing. Sure enough my 1st time out on the beach I get stuck. front wheels wasn't providing any power to spin the wheels. But the rear no problems.
I've read a bunch of post's and don't exactly get a clear answer. The issue I'm having is my 4WD isn't getting power in front wheels. I've put the front wheels off the ground and hand spun the front drive shaft w/o 4WD switch on. The front drive shaft spins freely and front wheels do not turn. Next thing I did while wheels still off the ground I put the 4WD switch into "4WD Auto". Now when I spin by hand the front drive shaft the wheels turn. But if I hold the tire from spinning I can still spin the front drive shaft w/o much resistance at all.

I read somewhere on here that it might be something call "auto hubs"... if that is indeed what it is, where are they located?

Any help would be greatly appreciated.

 

[Dave 1955]

I know the 95's had vacuum hub engagement .
Look on the right side of the axle housing(passenger side) and see if there is gadget there with wires or hose's. If there is that prolly is your problem.

Strange system..fronts wont work till the rear tires slip.

 

[artray724]

ok, I just looked and took some pics. There is the round thing with 3 wires coming out of it. Don't know what it's called or what it does.
I also just found a hose that wasn't attached to a nipple on the top of the front axle casing. One end attaches to that and the other end has thing thing plugged into it. see pics below

 

[artray724]

see my pics I just posted

I know the 95's had vacuum hub engagement .
Look on the right side of the axle housing(passenger side) and see if there is gadget there with wires or hose's. If there is that prolly is your problem.

Strange system..fronts wont work till the rear tires slip.

 

[Beargap]

I know the 95's had vacuum hub engagement .
Look on the right side of the axle housing(passenger side) and see if there is gadget there with wires or hose's. If there is that prolly is your problem.

Strange system..fronts wont work till the rear tires slip.

+1. The Control Trak system had a 2WD/4WD-Auto/4WD-Lo arrangement through 1996 and that included a vacuum operated front axle disconnect, and that is likely the problem. Good chance the vacuum line is just off somewhere. In 1997 and later the system changed to 4WD-Auto/4WD-Hi/4WD-Lo operation with no front axle disconnect and the ability to lock the transfer case by selecting either of the non-auto positions, making a much better system for off-road or snow.

Also note, the 4WD-Auto utilizes an electric clutch in the transfer case to connect to the front drive shaft. With power off, I would not expect there to be any connection.

 

[artray724]

After connecting that hose in the pic above I put the truck on blocks. All 4 wheels were off the ground. Started it and put it in 4WD. All 4 wheels spin. The front driver side doesn't spin as fast as the others. Also I was able to stop both front wheels from spinning while in drive and at idle. Are you suppose to be able to stop the front wheels from spinning? And it felt like little pulses when I was holding it from spinning.

 

[Beargap]

Yup. Those little pulses are the clutch pack connecting. It does that many times each second, say maybe 60, and the length of time it stays engaged runs from 10% up to 100% in roughly 10% steps in Auto mode as increasing front traction is called for.

 

[artray724]

so what does that mean? Are you suppose to be able to hold back the wheels from turning while in 4WD? Why don't I have torque power in the front when I'm on the sand?

Yup. Those little pulses are the clutch pack connecting. It does that many times each second, say maybe 60, and the length of time it stays engaged runs from 10% up to 100% in roughly 10% steps in Auto mode as increasing front traction is called for.

 

[Beargap]

so what does that mean? Are you suppose to be able to hold back the wheels from turning while in 4WD? Why don't I have torque power in the front when I'm on the sand?

The way the Auto system works is to measure the axle speeds for front and rear. If the rear is turning faster than the front, the engagement time of the clutch pack pulses increases in stages until the rear is no longer faster, then starts backing off again...in other words, the rear has to spin for the front to get more torque. If, in a '96 version, you switch to 4WD-Lo then the clutch pack is continuously energized, basically locking the transfer case like a manual unit, and the torque is split 50/50 front and rear. Not good for dry pavement where the front will move faster than the rear in turns, but good in poor traction. This all assumes your front axle disconnect is working properly and the clutch pack in the transfer case is not defective.

 

[artray724]

How would I tell if either of front axle disconnect is working properly or the clutch pack in the transfer case is working?

The way the Auto system works is to measure the axle speeds for front and rear. If the rear is turning faster than the front, the engagement time of the clutch pack pulses increases in stages until the rear is no longer faster, then starts backing off again...in other words, the rear has to spin for the front to get more torque. If, in a '96 version, you switch to 4WD-Lo then the clutch pack is continuously energized, basically locking the transfer case like a manual unit, and the torque is split 50/50 front and rear. Not good for dry pavement where the front will move faster than the rear in turns, but good in poor traction. This all assumes your front axle disconnect is working properly and the clutch pack in the transfer case is not defective.

 

[Beargap]

How would I tell if either of front axle disconnect is working properly or the clutch pack in the transfer case is working?

With the engine running, engage 4WD-Lo. That should lock the transfer case and engage the front axle (which needs engine vacuum). If the wheels turn the drive shaft with the truck in Park, it is likely the clutch pack. with the engine off but ignition on RUN, turning the rear wheels ought to turn the front drive shaft in neutral. If the drive shaft turns but the wheels don't, it is the vacuum disconnect.

I don't know if this is Ford procedure...I'm just suggesting a way to isolate the problem. Usually it is the front axle vacuum connection, but you never know...

All of the 4WD logic is in the GEM computer, which also controls wiper delay and such, but I'd think you'd see other issues if that was the problem.

 

[artray724]

ok, I will try this tonight when I get home. But it does sound like sorta the process I already explained in this thread earlier. Is the front vacuum connect in one of the pics I posted? Just so I no what I'm looking for.

With the engine running, engage 4WD-Lo. That should lock the transfer case and engage the front axle (which needs engine vacuum). If the wheels turn the drive shaft with the truck in Park, it is likely the clutch pack. with the engine off but ignition on RUN, turning the rear wheels ought to turn the front drive shaft in neutral. If the drive shaft turns but the wheels don't, it is the vacuum disconnect.

I don't know if this is Ford procedure...I'm just suggesting a way to isolate the problem. Usually it is the front axle vacuum connection, but you never know...

All of the 4WD logic is in the GEM computer, which also controls wiper delay and such, but I'd think you'd see other issues if that was the problem.

 

[artray724]

Ok I tried what you said Beargap. Everything checks out. I even went as far as taking the truck on the sand again. Now with it in 4low on the sand it is still not giving me any front wheel pulling power. At time I really gave it some gas and watched the tires spin. I can see the rear really spin turning up the sand much like a burn out but the front not doing a thing.

I don't understand when I had the truck up off all 4 wheels and in 4WD all the tired spun when in drive. I'm just not getting real pulling power from the front. What can that be??

ok, I will try this tonight when I get home. But it does sound like sorta the process I already explained in this thread earlier. Is the front vacuum connect in one of the pics I posted? Just so I no what I'm looking for.

 

[Beargap]

Ok I tried what you said Beargap. Everything checks out. I even went as far as taking the truck on the sand again. Now with it in 4low on the sand it is still not giving me any front wheel pulling power. At time I really gave it some gas and watched the tires spin. I can see the rear really spin turning up the sand much like a burn out but the front not doing a thing.

I don't understand when I had the truck up off all 4 wheels and in 4WD all the tired spun when in drive. I'm just not getting real pulling power from the front. What can that be??

Sort of sounds like maybe the clutch pack is weak in the transfer case, but frankly I am guessing now. If everything switches in correctly as you describe, but you can't get any traction from the front under load, then maybe that clutch pack is slipping. My '97 with manual transmission is all but unstoppable when the transfer case is locked like that, but we don't have sand here...just mud and snow and rocks. When the transfer case is locked, in 4WD-Lo in your case, you should have a lot of problems turning a corner on a dry surface...it will nearly stop your truck. Don't do that going very fast, though, as it could break something...that reminds me, the transfer case clutch starts releasing at higher speeds, which I thought was by the speedometer link not the axle speed. If you are spinning the rear wheels very fast perhaps that is fooling the logic into thinking you are going fast and it is backing off on the clutch pack engagement time.

 

[artray724]

I've tried the whole sharp turn at low speed in 4 low. I know what it's suppose to feel like but it doesn't feel the way its suppose to feel. When I say giving it gas, I don't mean getting up to a fast speed. I was probably doing 5 mph and then hitting the gas a little maybe pushing it up to 10-15 mph.

At one point I had all 4 wheels up, put in 4WD auto and into drive. all wheels were spinning but the driver side wasn't spinning as fast. While still in drive and in 4WD auto I was able to stop the front wheel from spinning. Now while holding the wheels from spinning the front drive shaft was still turning. To me that makes me think that the T case is working fine but the front Dif not so much.

You mention a clutch pack, this is in the T case? Is there on in the front dif?

Sort of sounds like maybe the clutch pack is weak in the transfer case, but frankly I am guessing now. If everything switches in correctly as you describe, but you can't get any traction from the front under load, then maybe that clutch pack is slipping. My '97 with manual transmission is all but unstoppable when the transfer case is locked like that, but we don't have sand here...just mud and snow and rocks. When the transfer case is locked, in 4WD-Lo in your case, you should have a lot of problems turning a corner on a dry surface...it will nearly stop your truck. Don't do that going very fast, though, as it could break something...that reminds me, the transfer case clutch starts releasing at higher speeds, which I thought was by the speedometer link not the axle speed. If you are spinning the rear wheels very fast perhaps that is fooling the logic into thinking you are going fast and it is backing off on the clutch pack engagement time.

 

[Beargap]

I've tried the whole sharp turn at low speed in 4 low. I know what it's suppose to feel like but it doesn't feel the way its suppose to feel. When I say giving it gas, I don't mean getting up to a fast speed. I was probably doing 5 mph and then hitting the gas a little maybe pushing it up to 10-15 mph.

At one point I had all 4 wheels up, put in 4WD auto and into drive. all wheels were spinning but the driver side wasn't spinning as fast. While still in drive and in 4WD auto I was able to stop the front wheel from spinning. Now while holding the wheels from spinning the front drive shaft was still turning. To me that makes me think that the T case is working fine but the front Dif not so much.

You mention a clutch pack, this is in the T case? Is there on in the front dif?

There is a clutch pack in the T-case that applies power to the front drive shaft. I thought the front axle vacuum disconnect was a mechanical connection (my 97 doesn't have that as the front axle is always connected), but if it also a clutch that could be the trouble. Failure of the front axle disconnect is common in vehicles that have that. GM users have a mechanical cable-operated mod to address that. Other than knowing it exists, I don't have much info on the 96 and earlier Explorers.