I don't know why, but my Ram's mpg does not change at all driving in 4wd regular mode, as long as it's wet or snow. My Toyota Tacomas would guzzle in 4wd. Auto mode I believe uses a clutch that allows for some slip before hooking up. Try on a wet road at 55 mph, reset mpg, drive enough for mpg to stabilize, maybe 5 miles, then put it each 4wd mode. As long as the road is relatively straight, don't think you'll see much difference. The problem with the regular 4wd, on slippery surfaces, the ass end can come around.

 

That is a good point. I dont actually know if my mpg is effected by 4auto verses 2wd. I have never really checked. Our last Durango Limited had 4 Auto and we never used anything else for 8 years. Its perfect for this time a year when you never know what the road conditions may be.

 

Not sure if post #4 answers your question



http://www.ramforumz.com/showthread.php?t=41954

 

This is my understanding of it, corrections welcome

In the ' Auto ' Mode 70% of the power is to the rear until
a slip is detected then it ' Automatically ' transfer the power
where it's needed.

 

My guess is that either the temperature sensor, or associated wiring in the transfer case is faulty.

The BW 44-44 t-case in your Ram is an on demand 4wd system. Even in the 4wd lock, or 4wd low settings, the truck remains in 2wd, until the rear axle slips. Once slippage is detected an electromagnetic clutch inside the t-case, engages the front axle. Once off the throttle, the clutch disengages, only to engage, once you are back on the throttle and slippage occurs again. In addition, this electromagnetic clutch reduces power to the front axle when the front wheels are turned. As you can imagine, the constant locking and unlocking of this clutch, and the slippage that results from this, heats up the t-case fluid in a hurry. To protect the t-case, Ram limits power and even disables the 4wd altogether, once the t-case gets too hot.

It's a horrible design, and has noplace on a full size truck.

There are lots of threads on this subject such as this one:

http://www.ramforumz.com/showthread.php?t=192481

From

http://www.ramforumz.com/showthread.php?p=1726108#post1726108

VERY similar to the BW4406 Torque on demand (TOD) used by ford in the 90's. They had clutch problems that some are seeing where there is no 4wd in auto or locked. Tire wear caused issues as in .250 of wear difference.

 

"From 2011 on, Dodge has offered Ram 1500 pick-ups equipped with the BW 44-44 transfer case. The 44-44 transfer case is a computer controlled “active”full-time transfer case. A wet clutch pack in the transfer case can split torque between the front and rear axles depending on the range selected by the driver. There is a 4WD low range that provides a 2.64-1 gear reduction for off-road use.

A dash-mounted selector switch allows the driver to select five ranges, which include 2High, 4WD Auto (which can be used on dry pavement), 4WD Lock, Neutral, and 4WD Low. The shift selector switch feeds range selection to the Drive Train
Control Module (DTCM), combined with input from the transfer-case mode sensor and input from the truck’s bus to determine if a shift is permitted within the design parameters.

If the shift command meets the software requirements, the externally mounted shift motor will shift into the desired range. The wet clutch is electro-mechanical design, using a clutch pack and a ramp-and-ball system to engage the clutch pack to send torque to the front axle when a slip is detected (difference in axle speeds) in 4WD auto range. In the other 4WD ranges, the clutches are locked to achieve 4WD ranges.

There is NO mechanical lockup, and the clutch pack has to deal with all the torque transfer. Herein lies the problem. Many customers in the Snow Belt and Canada are using this setup for snow-plowing. Field reports show that the clutch pack cannot handle the abuse put on it by plowing snow or heavy offroad use, such as beach-driven vehicles.

The electromagnetic clutch with ball-and-ramp design has been around for a long time in the BW 44-05, 4406, and 4411. The 44-44 clutches have a narrower band of friction material than the aforementioned models, with a thinner pressure plate, to add more clutches to the pack. This works fine in vehicles that are not used for snowplowing or heavy offroad use on beaches, but cannot live under the stress of that usage.

One fix is to swap in a BW 44-45 transfer case, which is an electronically shifted part-time transfercase, which is a direct bolt in. The computers are the same in both, but nevertheless, this is a very expensive undertaking. To get around this, we have developed a kit to mechanically lock up the 44-44 in 4WD ranges to prevent future clutch failures.

Removing the 4WD Auto mode means that the vehicle can no longer be driven in 4WD on DRY pavement, with the plus side being that the driver can plow snow or beach drive to his heart’s content without clutch failure. This kit, available next month, will cost approximately $800 and requires disassembly of the transfer case. Keeping your commercial customer on the road earning money from his vehicle is job No. 1."

http://www.transmissiondigest.com/me...s/TD201504.pdf