It sounds both the locking diffs are controlled automatically by the computer of the car, switching back and forth between open and lock

Is there any way these diffs can be manually controlled?

Is there any mode in the "terrane response " program which will keep one or both diff "Locked"?

 

No, there is no manual control to permanently lock the diffs (like on a jeep or bronco). I think 'rock crawl' will mostly keep them locked, however it will also put you in off-road height mode if you have air-suspension

 

Yes.

If you have it, configurable terrain response allows the driver to lock the center and rear e-diffs. You can set up a profile with them locked/unlocked.

Otherwise they will lock/unlock (with an infinite spectrum of partially locked) as needed. The latter being controlled by the car's smarts.

 

I thought in configurable you only have the option of 'automatic' or 'slip-limited' for the differentials. I'll have to go look again. I wouldn't think 'slip-limited' means 'locked'?

 

As others have said, you can choose Auto, Lock Center and Lock Center & Rear. Even if you manually lock the diffs, they are still infinitely variable and can still partially unlock. This is my screen on OS 4.1.1

 

They can not be locked in an override mode even if the configurable setting says locked. The ecu still is in control as stated above. Luckily in model year 23, the awd system was changed to permanent rear wheel drive instead of a center differential, so if combining with a selectable air locker in the rear, a broken axle or cv will not leave you completely stranded.

 

@sarek of course you're basically a God on here, but can you explain a bit more about this -- "Luckily in model year 23, the awd system was changed to permanent rear wheel drive instead of a center differential,"

I had not heard that. Is that across the entire range?

 

Just when I think I may have an inkling of understanding on these mysterious ediffs @sarek comes along to make me feel like the moron I am.

All this time I’ve had my saved TR profiles and never thought to check to see if indeed the diffs remained locked. A quick driveway test confirms my idiocy.

seems like a completely pointless option. Letting a driver think they are locking their diffs when the ECU retains control.

I’d love to know what selecting locked diffs actually does. Perhaps it sets their default position to locked but still allows them to selectively unlock as needed. What TF do I know?

OP my apologies for the bad info.

 

Yes, it looks to be accross the entire range. The D300 (diesel non US) seems to have had the permanent rear wheel drive system since the beginning of production. The rest have all had the center differential until 23.5

The center differential system which is in all of the US production vehicles until model year 23 (p400) and 23.5 ( p300, p400 ) is set up like this. Power comes from the transmission and enters the transfer case. There it goes into a differential that can be variably locked by the traction control system. So for example, when no locking is applied, the differential puts power 50/50 to the front and rear driveshafts as long as there is no slippage or loss of traction just like any open front or rear differential. If you lift a wheel or slip im mud, just the slipping wheel spins and the other doesn't turn. Path of least resistance. So driving down the highway, the vehicle is in an all wheel drive state with the center differential mainly not locked and power is split to all wheels. The center differential is what allows the driveshafts to turn at different speeds when turning the vehicle to prevent binding since wheels turn at different speeds when rounding a corner. In a situation where 1 axle breaks or cv joint. The broken part has the least resistance and it will only turn. And you can not move. You can sort of move but the computer keeps unlocking the front and center diffs , so you just barely move when going straight. But turns are almost impossible. The center differential uses clutches to variably apply friction to the differential to prevent slipping when needed in turn locking it . The rear factory locking differential behaves very similar.

The 23.5 and up system works like this. Power comes from the transmission into the transfer case and is permanently connected to the rear driveshaft. There is no differential in the transfer case. It is what they call permanent rear wheel drive. The tcsse has a torque on demand unit that puts power to the front driveshaft when needed. It uses a similar clutched unit to do this, but the vehicle will always have power to the rear no matter what. Not the case with the earlier unit. Another difference is that the permanent rear wheel drive system has a front axle disconnect built into the front axle tube. At highway speeds the system will actually completely disconnect the front axle. These systems have a much better MPG because of this. I have actually driven one of these without a front driveshaft installed! You can not do that with the previous system. So as i stated in my post previously, if you have this system with our Sarek selectable rear air locker, you can still drive even if you break any one of the axles or CVs . With the factory rear locking diff you can break a front, but not a rear.

I believe the later system has many benefits. I really wish i had this system vs the center diff system that i have. I have broken an axle and it is not a good day. I always want to be able to try to drive off the trail even in 2 wheel or 1 wheel drive vs becoming a major burden on my friends trying to drag me off the trails.
​​​​​​Also, because of the axle disconnect, both front axles are the same part number, so u only need one spare for the front. Also much easier to replace the right axle from the previous system. The MPG gain is also a nice bonus.
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So do you think this new set-up would perform worse in slick situations or slip tests where perhaps 100% of the power needs to go to one front wheel? Also, I have a 2024 and I sure don't see a fuel benefit.... 😬😁