[Austin]

ABS still works when VDC is disabled.
ABLS still works when VDC is disabled.

ABLS functions in both 2hi, 4hi and 4lo. If you have the rear end locked, ABLS is effectively disabled for the rear only (obviously) as there can be no differential movement between left rear and right rear. ABLS still functions for the front end with the rear end locked.

ABLS acts to limit wheel slippage in side to side relation, not front to rear.
Example: Truck is in 4hi, right front wheel (only) has no traction. ABLS will apply brake force to that wheel only to transfer torque to the left front wheel. The rear wheels are not affected in this example.




Here is something I posted in an earlier thread:

To say it more precisely, an open differential will deliver equal amounts of torque to both sides.

This means it's important to understand torque - torque is a twisting or turning force.

For torque to be generated, there must be something to push against. If there is no resistance to turning a wheel, then very little torque is generated to turn the wheel - effectively none. With an open differential, the equal amount of torque is applied to the other wheel - effectively none.

That means that when one wheel leaves the ground or is in a zero traction situation, that wheel requires effectively zero torque to turn it. An open differential delivers exactly that amount of torque - effectively none - and it delivers that amount of torque to both sides.

Remember, to generate torque, there must be some resistance to turning or twisting.

Active Brake Limited Slip simply gives the open differential something to push against. When one wheel leaves the ground or is in a zero traction situation and begins to spin, ABLS will act to apply brake force to that wheel and that wheel only. To the open differential, this has the same effect as having traction with that wheel - there is now something to push against, allowing torque to be produced and delivered equally to both wheels.

Most reports of ABLS I've read indicate it works as designed. If, in fact, it *does* work as designed, it's the neatest thing since sliced bread. The driveability and low maintenance of an open differential with the traction of a limited slip differential. You get to have your cake and eat it, too.

That's how ABLS and open differentials work.



VDC is the system responsible for reducing engine output to limit wheelspin.

When you mash the gas and one rear wheel begins to spin (begins to lose traction), ABLS acts to apply brake force to that wheel - allowing the open differential to generate torque and be delivered equally to both wheels - giving torque back to the wheel with traction.

At this point, if both wheels spin and VDC is turned on, VDC will act to reduce engine output to reduce wheel spin. If VDC is turned off, you'll sit and spin both rear wheels.