Actually, it can be as bad as 1 wheel drive. You have to let the wheels spin long enough to trigger the ETS which will then apply brakes to any spinning wheel. You should see the ETS light come on when the system is actuated, less than 10 revolutions should do it.

You DO NOT have to hold the throttle to the floor! When the ETS stops any and all of the spinning wheels, the power is automatically routed to the remaining wheels that have traction. This will happen in high or low range, you will just have more torque available in low range.

It is kind of a weak system because anytime you apply brakes to a wheel, you are sapping power from the drive train. Locking differentials cost a lot more money though. Of course if only one wheel is getting traction, locking diffs will not help you either!

Jim in Phoenix