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Discussion Starter · #1 ·
i have a 08 xlt escape with 4 wheel drive. i have noticed that the rear wheels dont seen to engage in slippery snow. that has got me stuck in snow 2 times now. i turn off the stability control, and that helps, but still the rear wheels still dont want to turn. is that normal? or am i doing something wrong?
 

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It is not normal. The back wheels should get power if the fronts are spinning and you have a 4x4 Escape.
 

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I'm no mechanic so I can't answer what's wrong. There have been a few similar threads so you might want to try some searching. I'm sure a few more knowledgeable members will chime in...
 

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Hello Vansprink;

A very unusual problem. The intelligent 4 wheel drive system in the 2005+ Escapes are pretty much bullet proof (and a very good system compared to other manufacturers).

The only thing I can possibly think of that may not throw a code and result in the rear wheels not engaging is the active torque coupling in the rear differential. The simplicity of the system makes for very few problems; if the driveshaft spins faster than the wheels are turning, the coupling locks up a friction plate in the rear axle which engages the 4WD.

You can mention this to your service dept and they may be able to either confirm or exclude this as the problem.

Cheers, Kai
 

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The 4WD system currently used engages every time you leave from a dead stop regardless of road conditions. The PTU turns the driveshaft all the time. A electro-mechanical clutch in the rearend transfers the power to the rear wheels.
 

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Short answer is no. You could do the 12 V congruency test across the leads of the connector on the diff but this is not likely the problem. If the wire was broke or the leads bent and not making contact, it would throw a code.

The reason I recommend not going any further is that with your '08, it is still under the factory powertain warranty ... any "tampering" may be a reason for them to deny warranty coverage.

Go to a different dealership and have them trouble shoot the issue.
 

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The Haverstraw Man said:
Some people believe that if you remove the fuse for the AWD to work you will get better gas mileage. I would at least check the fuse to make sure it is there or maybe blown.
I know somebody that drives a '06 Hybrid that removed the fuse and claims 1-2mpg increase. Removing the fuse will light up the "wrench" dash icon.
 

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Discussion Starter · #11 ·
ok, so i called by dealer and asked some questions. first of course thay have no idea what it could be. service advisors dont have a clue. and second, powertrain warrenty is up a 60,000 miles. mine has 89,XXX. they told me there is a friction disc that spins then engages rear wheels. So what does my escape really have, Friction disc, or magnetic clutch?
 

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Your '08 has friction plates (clutch).

My best advise, bring it to a different dealership to troubleshoot the problem (don't get too discouraged yet). If it is the clutch, it is not serviceable ... Replacement is the only option.

**Addendum - Thanks Bill :thumb: "ATC" is the terminology I was looking for :?
 

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vansprink said:
ok, so i called by dealer and asked some questions. first of course thay have no idea what it could be. service advisors dont have a clue. and second, powertrain warrenty is up a 60,000 miles. mine has 89,XXX. they told me there is a friction disc that spins then engages rear wheels. So what does my escape really have, Friction disc, or magnetic clutch?
All Escapes since '05/'06 when they went from a hydraulic unit to the electro-mechanical clutch. I have no idea nor do they about a friction plate.

I can provide an explanation of operation right from the manual if you care.
 

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Discussion Starter · #14 ·
I would like to know how the system really works, it might help me better understand enough to talk with a mechanic. so if its a electro-machanical clutch. mabie its something really simple like a loose wire or conection. i did check the fuses and there ok. like i said no warning lights.
 

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vansprink said:
I would like to know how the system really works, it might help me better understand enough to talk with a mechanic. so if its a electro-machanical clutch. mabie its something really simple like a loose wire or conection. i did check the fuses and there ok. like i said no warning lights.
From the '08 Ford Escape Workshop Manual:

Principles of Operation
The vehicle is equipped with an All-Wheel Drive (AWD) system, also referred to as Active Torque Coupling (ATC), that is always active and requires no driver input. The system has no Mode Select Switch (MSS).

The system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected or if the vehicle is under heavy acceleration (high throttle position), the AWD system increases torque to the rear wheels to prevent or control wheel slip.

The system consists of a Power Transfer Unit (PTU), 4X4 control module, rear axle and a solenoid actuated ATC device. Based on the amount of current sent to the clutch, the module varies the torque sent to the rear wheels by sending a duty cycle to the ATC device, located inside the rear axle. For concerns with the PTU, refer to Section 308-07B.

The 4X4 control module also provides the brake system with its current clutch duty cycle and determines whether or not the brake system may take command of the clutch duty cycle.

NOTE: The ATC solenoid is not repairable. If a new component is required, the ATC solenoid and rear axle are installed as an assembly. Refer to Section 205-02.

The active, on-demand AWD system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the ATC solenoid that delivers the desired torque to the rear wheels.

Specific inputs to the 4X4 control module are:
• Accelerator pedal position via the High Speed Controller Area Network (HS-CAN)
• Transaxle range from the Transmission Control Module (TCM) via the HS-CAN
• Brake system status from the ABS module via the HS-CAN
• Wheel speed from all 4 wheels from the ABS module via the HS-CAN

4X4 control module outputs are:
• Solid-state clutch (pulse-width modulated signal) to the ATC solenoid
• Percent of torque transfer commanded signal to the ABS module via the HS-CAN
• Torque request available signal to the ABS module via the HS-CAN

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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I have the same problem with a 2005 escape I recently purchased. 4x4 light comes on if I accelerate then flickers and goes back off. Abs light is on and pads are good. Brakes pulse lighty when stopping. Fuel pump was just replaced but throws two codes that come back on in a few miles after being cleared. Engine runs good, trans shifts fine.
 
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