That's true, but the absolute speed would irrelevant if they compared the differential rotational speeds of the rear wheels, though I guess with rear-only ABS they have only one sensor at the center?

But of course, on slippery roads, quite often the rear wheels lock up due to braking forces on slippery surfaces and forward weight transfer (though trucks used to have brake proportional valves that reduced rear braking when the rear end rose on braking) , so the front speed would be far more effective.

I could probably access Live Data on the scanner easier than pulling a wheel to read the wheel speeds for those equipped w/ sensors.

I do know I didn't see the usual ABS unit with multiple brake lines and an electric motor under the hood.

Thanks for the hint!

Bob