Haven't checked fuses...
Haven't seen the disablement under heavy acceleration, just slipping...

 

By "lockup" I assume you mean engaged and I assume you are using a SG-II to monitor 4WD torque? IIRC, some Escape MY had a full lockup setting, do you mean that? Have you always monitored 4WD torque?

Might seem like dumb questions but on my 2009, just because I'm on snow doesn't mean 4WD torque as it does engage from a dead stop but by 30MPH, it's OFF.

 

The lockup he is referring to is where the system locks up instead of letting the clutch slip to reduce heat. Something is getting hot or thinking it is getting hot. His actually goes so far as to fully disable the 4wd because of the heat signal.

We found that his rear end was 8 ounces low on a system that only holds a little over a quart, so we're going to see if that was the issue. Next step is to see if the heat is real if the problem persists.

 

I see! That condition which has been discussed elsewhere is mentioned in the shop manual describing the 4WD's operation but how is a heat condition detected and how does the operator know?? There are no sensors in the rear diff and no dash icon listed for my 2009 at least.

 

It actually isn't really a dash icon, they do it the way Chevy did on the pickups in 2001 where it will actually list a message in the message center. Basically he got a readout on his dash in writing that I believe came from the odometer section. The first message informed him 4wd locked, the second informed him 4wd disabled entirely. I believe the heat sensor is integral to the junction box that is back there that controls it. I don't think you can change just the sensor.

 

The 4WD module is in the center console, I've been in there to put a scope on its output to figure out how it worked years ago which is actually how I ended up finding this forum. Nothing but two wires goes back to the read diff to operate the clutch. Unless it measures the DC current draw of the clutch coil?????

 

Drained the transfer case lube. Black & very dirty looking. About half of the required 12 ozs. Curioulsy no indication of leakage, drippage, etc. Since this unit is just a set of gears I don't expect to see any improvement after refilling. No silvery flakes or pieces of gear in the fluid drained...

 

It is very thick this time of year, I'm not overly surprised you only got about half of it out. I am surprised it was black since you'd already changed it before. Did it smell burnt at all? No metal is a great sign. These generally have the bearings in the ptu fail and then that takes everything else out. A failure almost always has metal shavings.

 

I let it drain for several hours... Smelled bad, 'spose the balck is carbonization. Putting the lube thru a coffee filter to see what gives. This is actually the third time I will have changed the lube in this. Roger on the metal shavings. Will use an inspection scope to see if I can see anything looking in the drain or fill holes.

 

Well, my guess is if the level actually was low you got toasty but didn't seem to damage anything yet. I wouldn't say that's your issue since I don't believe there is a sensor hooked up to the ptu at all for temperature or anything for that matter. I think it was just a happy coincidence that you got pointed in that direction likely a few thousand miles before it went kaboom.