Can anyone explain how the 2002 4Runner Limited 4x4 multi-mode system works? Do the axles lock like with ARB lockers? Does the transfer case lock? How does the system function? Can ARB lockers be added to the front or rear axles? Do they need to be?

 

the multi-mode system is basically an all wheel drive system with a lockable center differential. This allows the front and rear axles to spin at different rates and enables its use on dry pavement. Previous non-multimode systems were part-time 4WD, meaning they couldn't be used on-road because they lacked the center differential. Locking the center differential on a multi-mode system transfers the torque 50/50 to the front and rear axles - exactly the same as the part-time systems, except with the added feature of being able to unlock it. With the multi-mode system, came the added Active-TRAC feature. With ATRAC, it is possible for the ABS system to sense slippage and brake the slipping wheel "in theory". In theory because these systems never work as advertised.

When people add lockers, they're referring to the front and rear differentials. These differentials transfer torque side-to-side on your front and rear axles. Your front and rear differentials are still open. Do you need a locker? It depends on where you want to go with the 4Runner. Only you can answer that question.

 

We spend a lot of time in Mexico on hard washboard dirt roads and on the beach and in sand- not much rock crawling- 80% highways and streets, 10% dirt/mud/washboard roads, 10% small dunes, sand , and beaches. With this type of use, would we benefit from a locking system?

 

I have been on several trail runs with a 2002 with active trac. It did all of the obstacles the rear diff locked rigs did. Its pretty interesting to see it work when traction goes away. It uses the brakes to stop or slow down a spinning wheel so power goes to the other on that axle. It looks a little spazzy when all 4 are struggling to find grip, it goes into what I call 'Squirrel Mode' where all four are getting alternate brake and power pulses several times per second. It looks like a squirrel or rabbit running along but it always gets over the obstacle. I have never seen it in mud.

Its no substitute for a true locked rear diff, the 2002 had to use more momentum to bounce up things and sometimes the rear would bounce side to side a little requiring quick steering corrections. The stuff I saw it on was mostly rock faces with gravel or sand on top and rutted loose gravel hills.

 

Very interesting. I have noticed that when I am on winding washboard roads that the VSC system also kicks in to prevent spinouts- Even at 40-70 mph, going into a 4 wheel drift, it is difficult to lose control- the ABS works with the VSC and recovers control of the vehicle-