The ohm meter test won't help here. If there was a break in one of the wires, that would be detected by the computer. It would turn the system off, set a diagnostic fault code, and turn on the yellow warning light. What you have is a system with no electrical defects; only a weak signal that's dropping out. The computer interprets that as that brake locked up. Up till now, I haven't heard of a rear sensor at a wheel causing this, but it can be caused by a single rear sensor when all you have is one on top of the rear differential. Those can develop fuzzy metal particles stuck to the magnet. That "hair" interferes with the passing teeth on the tone ring's ability to alter the sensor's magnetic field and generate a signal. You should have the two individual rear sensors. They are of a similar design as those on the front.
The most effective way to pursue this from here is to find a friend with a scanner so you can watch what's happening to the speed signals as you drive. One has to be dropping to "0" when you're still moving.
Since all magnetic sensor signals become weaker as what's being detected slows down, all ABS systems are designed to stop operating below from 9 to 15 mph. Below that, all signals on all car models will be to low to read.
The only other thing common on GM vehicles is very slight, normal play develops in the front wheel bearings allowing the tone ring to move away from the sensor. This only applies to front-wheel-drive cars, and the problem often returns in as little as 15,000 miles after the bearing assembly was replaced. They used a different style wheel speed sensor. People have reported they've solved this problem on trucks by replacing the entire wheel bearing assembly, but I've always attributed that to they had that rust under the sensor that they weren't aware of.
Wednesday, December 29th, 2021 AT 1:38 PM