We discussed this before about temperature. The following is from the workshop manual section about 4WD operation.

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Heat Protection Mode

During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.
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There's no mention of a visual dash indicator of this condition. If locked mode means 100% rear wheel torque to cool the ATC. One of their other test points for 4WD operation is to command 100% rear wheel torque and if the vehicle resists turning, it's working correctly. If it overheats, goes into locked mode which causes steering problems. That's not good.

I wonder how temperature is detected in the rear end ATC unit since no sensor is there????

 

There was a period of time wherein the design engineers had decided, and accepted, that 200HP would "hit the wall" insofar as FWD vehicle engine were concerned. It was thought that beyond 200HP there would be too many instances of loss of directional, inadvertent loss, due to the use of too much engine torque for even highly tractive conditions.

Then along came Cadillac with the extraordinarily high HP/torque rating of the NorthStar engine but with automatic derating, dethrottling, of the engine at low speeds an in lower gear ratios.

TRAC was soon to spread throughout the FWD product set.

Obviously, moving a portion of the engine torque to the rear, EXTRA, wheels is yet another way of allowing a high torque engine to be used in an otherwise unsafe FWD vehicle.

 

I thought we had earlier concluded that the overheat problem did not apply to later model years of the FEH. I also thought that there was an indicator to warn the driver on the earler models. And yes, fully locked mode would allow the dual clutch to cool but the high stress would become even greater for the PTO ring and pinion.

 

All I can say is that's a direct quote is from the '09 Workshop Manual. There is a 4WD icon in the upper left corner of the dash but nothing is mentioned about it anywhere!

There's only two wires going back to the ATC unit in the rear end and they operate the clutch, so that's why I said there is no sensor of any kind there to sense temperature.

 

Two wires....plus 2 grounds..??

Not by any means saying, concluding, that's how it works.

 

One is B+ and the other is common(Ford calls it RTN) or a floating ground, it doesn't use chassis ground.

 

Okay. But I would assume that to mean that the most current FEH models are not subject to the overheating circumstance since there is apparently no way for the driver to "know".

 

I hope so but the same info is in the 2010 workshop manual also!

 

From you know who:

"We all already know that the early FE/FEH F/awd versions were prone to overheating"

Naturally the poster can not back up this statement with evidence and is incapable of producing any real world data supporting this.

 

wptski: Regarding your comment about leaving out the most important part of the discussion on slippage…
If you understood engineering you would realize that this is almost an irrelevancy.