Feathermerchant

The truth is that if you spin both rear wheels, the truck will try to switch ends. Spin one wheel and you're OK. If you need the rear axle locked to get started, fine. Unlocking it at 20 mph should be fine.
In what case do you need it locked over 20 mph?

MT-Ford

Mostly for deep snow or mud, under certain conditions.

cbr600rx7

A lot comes down to the situation. Where you live, what you use your truck for, terrain, drivers abilities to understand the situation, risk management, and common sense all play a factor. Assuming what works for you will work for every one is not a realistic image.

Personally my job requires me to go out in very nasty conditions often. When 20+ inches of snow in a 24 hour period is not uncommon and interstate I-81 is shut down. Some times I am pulling a trailer or might be unloaded and will need a little extra speed on a long incline. Or maybe I am on a gravel or dirt trail that's 20 miles long running up and over the side of a mountain where the truck decides it needs to open the rear diff and now I am getting wheel spin and bounce out of the rear. For me it would be useful at select times under controlled circumstances. And yes I do have experience with fully locked or spooled rears and they are not nearly as bad as many people claim. In fact my yota is spooled front and back with manual hubs up front and does very well.

And this is way out side of this topic but I am Not trying to sound like a jerk but have you driven a spooled or fully locked rear end in any conditions like I stated? . From my experience a locked rear end is way more predictable compared to a lunch box style locker that can lock unpredictablely.

cbr600rx7

Let's put the reasons why some one would do this mod to the side and focus on the best way to engage the rear ELD out side of the fords normal operating range.

Blackpony

^^^ This!! If someone finds a way in the code with forscan please share!!!

cbr600rx7

I see some products for the F250/F350 trucks. Of course the rear axles are different however the ford body harness especially in the 09-14 trucks seems to be very similar to include the raptor.

Nickerbocker12

I have a 2012 and I can lock the diff in 2wd, still kicks out once at speed..

CJS F-1

I've read that the raptor f-150's locker stays on over 20mph and some guys just buy the raptor 4x4/locker switch and also a module that comes with the raptor. They install it on their non raptor F150 and the locker stays on over 20 mph.

msgross

I thought that newer trucks (2012 and up maybe) can do this? My 2011 can't but someone mentioned finding a dash switch and control module from a newer truck and swapping it out. The 20mph thing would be a deeper problem, i'm not interested in that.

I've driven a truck with a full time locker (army CUCV) and they suck while turning.

Spiky

2013 FX4 locks in 2wd. Haven't tested it, but I'm sure it cuts out at 20mph or whatever.