OK. So the communication between the SLABS and the reader. Perhaps it is intended to not allow monitoring while at speed, for safety reasons...
Yep.
I connect my portable oscilloscope to the wires of one sensor at a time to watch its signal amplitude, steadiness of the sinewave waveform at any speed for diagnosing... found all good.

 

Give that man a prize. Once you hit a certain speed the ABS or SLABS monitoring is halted.

Just fix the hub/sensor.

 

You don’t need to go fast to monitor them. It’ll be pretty easy to compare a bad sensor vs a good one I used my iCarsoft LR2 to check a friends years ago & just a cruise down his 3/4 mile driveway at 8mph = 3 sensors within .01 of each other and one either flat lined with 0.00 readings or a reading that doesn’t stay consistent.

On his D2 it was going nuts and enabling the TC on that wheel. Then it would fault. I actually found debris inside the sensor hole (broken O-rings bits). Cleaned it out, reset the faults and he went nearly 2 years before it faulted on him again & then it was the shuttle valve switches vs the sensor.

 

Using all of your advice, I determined it was a bad front right wheel speed sensor. Replaced it and all of the 4 amigos went away!

Thanks again