Hi there. I have a 2021 Classic Warlock. Ever since I got the truck I have been confused on why it didn't come from the factory with a rear only Dif lock. There's only 2wd, 4 low, and 4 lock on my center console. I have been wondering if it is possible to jig up a switch that can lock the rear differential independently from the front while the truck is in 2wd. One would think that this would be totally possible as the truck can already lock the rear differential, albeit only simultaneously with the front differential. Any info on this would be greatly appreciated. Im sure somebody out there has attempted this right?
There is no center differential on these trucks and neither the front nor rear differential has a locking mechanism in it. I think perhaps you're on the new side when it comes to 4wd hardware and that's not meant as an insult at all, just an observation so let's get this sorted.
The word "Lock" in the 4x4 mode selector does not really carry the same meaning as the term "Locker" in the context of an axle's differential because there is no differential in this transfer case to begin with. Your transfer case always connects the output shaft of the transmission to your rear driveshaft no matter what mode you're in other than neutral. In 2H your front driveshaft is decoupled (100% disconnected) from engine torque. In 4H or 4L the front driveshaft is locked to the rear driveshaft and to the output of the transmission.
This is different from a locker that some trucks might have in their front or rear (or both) differentials because in an axle both wheels are already connected to engine power so the role of a locker there is not to couple or decouple the wheel to engine power, just to its neighbor wheel. That kind of locker was never offered in 4th gen 1500's so there is nothing to "switch".
These trucks were
available with a rear limited slip differential and they all (starting in ~2013) came with BLD & the BLD feature plays very nicely with the limited slip to make it behave almost like a full locker; albeit reactive rather than proactive.
You can't switch either of these things on or off, it's always there. BLD can only function on a driven axle so when you're in 2wd BLD is only going to work on the rear axle.
If you have the limited slip differential (LSD, also called "anti spin" by Ram) it's a clutch type unit and it has no controls or electronics it operates strictly on mechanical interference. When your rear wheels resist force from the engine the kingpin pushes against a cam (ramp) and that mashes clutches against the inside of the carrier and attempts to lock the left and right wheels together. On older trucks this feature would include a preload so that it can function when one of your rear wheels has zero traction but when BLD was introduced the preload was no longer necessary so they eliminated that which makes the clutches and oil last longer, reduces heat and saves a teeny bit of fuel. On your truck (assuming you have the limited slip differential) when the ABS tone rings identify one wheel is spinning freely it will apply the brakes to that wheel which will cause the limited slip differential to attempt to bind and behave like a real lock between the left and right wheels. Because of the involvement of the truck's service brakes this locks up the LSD much tighter than conventional spring-preload-only LSD's typically can.
BLD stands for Brake Locked Differential and that's Ram's (and Jeep's) name for off-road traction control. Ram didn't pioneer it (I think that credit goes to Mitsubishi) and they all work pretty much the same way and without getting too far in the weeds with it, it's just an off-road oriented calibration for traction control that remains active even when the speed-limiting feature of traction control is turned off. Just about every modern car will use individual wheel braking along with overriding throttle control to try to prevent wheel spin, keep the car driving in the direction you've pointed the steering wheel and hopefully send power to whichever wheel has traction - the difference that BLD brings to the table is that it continues to work when you use the button in your dashboard to turn off traction control. In that mode BLD doesn't attempt to limit throttle it only cares that both wheels on the same axle are going the same speed as each other so if you're in mud and leaning on the throttle when one wheel is spinning freely it will apply the brakes to that wheel and try to make the other wheel begin operating. You can look up videos on BLD on youtube most of them will show it working on Jeep vehicles but your 2021 Warlock has the same feature regardless of whether it has LSD.
It is not possible to (cleanly) turn off BLD with a switch, you could technically disable it by switching off your ABS entirely (or interrupting signal from one wheel speed sensor) but that would light up your dashboard and not reset itself automatically when you flip the switch back. You could also disable it using JSCAN or AlfaOBD, but that's a lot of steps on your phone not a simple on/off switch.
I think the implied question here is why you want to switch "locking" off/on to begin with. Is there something your truck is not doing well enough, or you just want the same switch your buddy's tacoma has, or something else?
