So the Owner's Manual mentions an overheat condition but there's nothing at all in the Workshop Manual or temperature sensor on the 4WD/ADW system shown in the Electrical Diagram Manual? This means that the Owner's Manual is incorrect.

The 2009 Owner's Manual doesn't mention anything about that but the Workshop Manual does but there's no temperature sensor shown in the Electrical Diagram Manual. The Ford Workshop Manual is incorrect.

I'm not trying to help either of you. I'm just trying to get to the truth about the so-called temperature monitoring of the 4WD/AWD system.

Curiosity about the workings of the 4WD system brought me to this forum after seeing your Scanguage pictures in another forum. The thread I started back then resulted in the modified coding that you "might" be using today. DesertDog got run out of this forum but I didn't.

 

There a couple of situations wherein a 2 wire system would work. Two individual circuits both relying on chasis ground for circuit return. Or...the ability to sense the magnetic clutch winding resistance during the PWM "off" periods. Making this latter a bit easier would be a few windings of nichrome wire in series, maybe integral to, the rear clutch "solenoid".

 

It is my understanding that the actual driver managed 4WD system was finally abandoned(***1) due to continuing failures from it being engaged manually (switch) when roadbed conditions did not warrant.

The Toyoya Venza used this technique initially. In 2010 Lexus, RX350, adopted this very same rear drive coupling technique but unlike the Venza with a driver operated switch so the driver could control the 4WD mode manually.

My bet at the time was that the RX350's manual clutch control would be abandoned within 2 years. Most of today's driver's have no clue as to when it is appropriate, or NOT, to engage an AWD, nor even a true (dog/sleeve center diffl clutch) 4WD system

The Porsche Cayenne now also uses the same technique, but to couple drive torque to the front.

***1 ECU automatic use only, rear drive coupling ONLY as a function of STRAIGHT-AHEAD low speed acceleration, the harder you accelerate, the higher will be the level of drive coupling to the rear. Should a front wheel show slippage, still, TC will INSTANTLY(***2) activate, dethrottling the engine and using the front brakes to simulate roadbed traction.

The RX350 now provides a TC....VSC disable capability in order to disable the TC enforced 4WD mode, such that the driver can now more easily make use of throttle "feathering" to maintain adverse condition roadbed traction.

***2 Keep in mind that even a momentary, ever so brief, loss of traction on the front can turn HAZARDOUS.

 

Oh, sorry, over-looked a point. These days one can easily have enough computing power on board to determine the level of HEATING present in the rear diff'l as a function of other KNOWN parameters, OAT, average roadspeed, PEAK and average engine torque...etc, etc.

 

Sorry guys, I don't care what wwest posts; I don't bother reading them because they are not worth considering. I'd have to read them to realize where they are wrong. If he occasionally gets some random item right, well, OK, but it isn't worth devoting any time to reading his posts. I prefer to focus on posts by owners who are sharing information or problems.

I happened to pick up the one in this thread because someone used the quote button...

 

Just because a person doesn't own a FEH doesn't mean they automatically know nothing useful. Some things are just plain car topics which are generic to FE/FEH.

 

With wwest, there is so much bad information that I just don't find it useful to try and read his posts to see if he is spouting nonsense. It just isn't worth the time.

 

Yes, if you don't have a "combine" it becomes hard to separate the wheat from the chaff...

 

I am starting to remember why I (and many others I bet) quit coming to this site.....trolls and the people who feed them....

Good luck folks.

 

Only the one troll that I know of. Bummer though, that one person can do so much damage.