Do 4th gen 1500 4x4s have "active LSD" - or not?

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Jebb

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I have seen several YouTube videos lately showing a 1500 4x4 stuck in the snow with one front wheel spinning, one back wheel spinning and the other two wheels doing nothing, i.e., the classic "open differential" 4x4 scenario.

I don't understand this. According to my owner's manual, my 4th gen truck (and I thought all 4th gen 1500s) has "active LSD" that uses the ABS system to apply braking force to the spinning wheel(s) thereby shifting the load to the wheel(s) with traction. AFAIK, the once very common clutch pack LSD offered by the factory appears to have been eliminated in favor of this "active LSD" system, at least on the 1500s.

I have been in slippery situations where I had one back tire in the mud and the other on dry ground. At least in my case, when the "mud" wheel started spinning the other one started pulling - as I expected. At least in my truck, "active LSD" seems to work. (And I am certain my truck does not have a mechanical LSD).

I also understand from the owner's manual that disengaging "Traction Control" does NOT turn off the active LSD - it only turns off throttle modulation. So, AFAIK, these trucks should not be spinning opposite wheels like this.

So what's going on in these videos? Did the YouTubers' pull their ABS fuses before making these videos - or does the "active LSD" system not always work?
 

JW2 Innovations

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When looking to buy my truck I found enough postings on this mentioning the build sheet answers what each truck has that I made it part of my search. VIN search your build sheet will answer what you have, then if you choose to test it to see if working right.
 

392DevilDog

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BLDS

Brake locking differential system.

They all have it standard.

The issue is the AWD transfer case....the one with 4wd auto selection is unable to put power to the wheel for the BLDS to work

That is why a lot of people dislike the 4wd auto transfer case.
 

392DevilDog

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That said. The BLDS is easily over ridden if you do not understand it.

You need to apply throttle and stay at that throttle. Allowing the wheel to spin, but not over rev, and stay at the same input so the system can work it's magic.
 

392DevilDog

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Anti spin differential is an option. Would affect the rear only.

The 5th Gen 1500 also has an available eLocker

Even the anti spin rear can cause only one wheel to spin in the rear axle. Once again...it has to slip in order to engage...and you need to control the throttle enough to get it to engage and stay engaged.

Even with all the nannies on newer vehicles...driver skill is still needed to completely enjoy the vehicle.
 
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Jebb

Jebb

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That said. The BLDS is easily over ridden if you do not understand it.

You need to apply throttle and stay at that throttle. Allowing the wheel to spin, but not over rev, and stay at the same input so the system can work it's magic.
 
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Jebb

Jebb

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Doesn't seem like a very good system if the driver has to "understand it" for it to work.

So if all these trucks have this why are they able to spin a wheel when in snow/ice? Like I said, I'm pretty sure this system DOES work on my truck. Haven't had it in snow but in mud the spinning wheel only spun one or two revs before the other wheel started pulling.
 

392DevilDog

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Doesn't seem like a very good system if the driver has to "understand it" for it to work.

So if all these trucks have this why are they able to spin a wheel when in snow/ice? Like I said, I'm pretty sure this system DOES work on my truck. Haven't had it in snow but in mud the spinning wheel only spun one or two revs before the other wheel started pulling.
What I mean is ...some people think you just floor a truck or feather the throttle in and out.

BLDS works great. I use it all the time

But, you have to stay steady in the throttle.

Have you read some of the questions people ask about 4wd and how to use it?

Read some...then you will get my point
 
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392DevilDog

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Haven't had it in snow but in mud the spinning wheel only spun one or two revs before the other wheel started pulling.
That is exactly how it works.

The issue being...people feel the spin and lift off the throttle.

Or they think they have to floor it to get out of the slippy.

Ease in to the throttle and stay steady...it slips, one to 2 revolutions and automagically the power is distributed and away you go.
 

392DevilDog

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On the various ram truck sites I am on there are about 5 posts about people not being able to engage 4wd low.

You have to understand...the truck needs to be in transmission neutral to make the shift.

What I mean by understanding how it works.
 
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Jebb

Jebb

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That is exactly how it works.

The issue being...people feel the spin and lift off the throttle.

Or they think they have to floor it to get out of the slippy.

Ease in to the throttle and stay steady...it slips, one to 2 revolutions and automagically the power is distributed and away you go.
IMO, that's actually better than the mechanical LSD I used to have for driving on the street in snow and ice. Most mechanical LSDs have some amount of pre-bias that applies torque to both wheels when lightly loaded. When you get on a super slippery surface, like ice, that pre-bias can be enough to cause both wheels per axle to spin/break loose - at which point you lose lateral stability. One minute your going straight, the next your backend slides out. Had some pretty harrowing corners on ice when I had my Eaton Truetrak diff! IMO, for street driving on snow and ice, it's better to have one wheel slipping a bit while the other is still guiding you straight. This "BLDS" system seems to do that pretty well.

Of course on other surfaces like mud and sand it's better to have solid power to both wheels of the axle. IMO, "E-lockers" offer the best of both worlds. Would be my LSD of choice if I had the $$$ to spend on it. I believe that's a factory option on the 2500s.
 

392DevilDog

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Not sure what your last paragraph says.

The 2019 and newer RAm 1500 5th gen has a rear eLocker available, standard on Rebel.

The 2500 trucks, PowerWagon has it standard front and rear...and now the new REBEL HD has the rear eLocker.

I think that is what you were mentioning?

I wish my truck had the eLocker.

But so far the anti spin and BLDS have kept me moving through all the forests of PA and even some harder trails on private land.
 

metalchewy

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My 4th Gen, 2010 TRX4 4.7 with LSD will spin all 4 tires in 4x4 High or 4x4 Low. Dirt, Mud, snow, pavement, whatever. After the rears start spinning both fronts kick in.

It does not have 4x4 Auto on the dial.
 

TomB 1269

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A lot of people up their trucks in 4low when stuck in snow..."Better throttle and wheel speed control". However, it you read closely this also disengages just about everything including the BLDS........
 

392DevilDog

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A lot of people up their trucks in 4low when stuck in snow..."Better throttle and wheel speed control". However, it you read closely this also disengages just about everything including the BLDS........
You sure!?!?!...I use 4wd low all the time. It works great in Pennsylvania State forest drivable trails...for, you know, tread lightly.

”Brake Lock Differentials (BLDs), which are incorporated into the Electronic Stability Program (ESP) algorithm. BLDs apply braking force to an axle's spinning wheel in order to provide an equal amount of torque to each wheel and deliver greater traction for rock-crawling over severe off-road terrain. A separate set of BLD calibrations is designed for off-road operation and automatically activates when driving in 4 Low”
 

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Anti spin differential is an option. Would affect the rear only.

The 5th Gen 1500 also has an available eLocker

Even the anti spin rear can cause only one wheel to spin in the rear axle. Once again...it has to slip in order to engage...and you need to control the throttle enough to get it to engage and stay engaged.

Even with all the nannies on newer vehicles...driver skill is still needed to completely enjoy the vehicle.
YUP, slow and steady wins the day.
 

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392DevilDog

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TFL Truck just made a video showing the brake locking in action. Shows the importance of giving it steady throttle as it takes a moment for the computer to really clamp down on the slipping wheels.
See, I do know what I am rambling about
 
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