In a recent development, the brakes on all 4 wheels lock up after the car is driven for a short while. WOn't move at idle, must be throttled up to maintain motion. Problem occurs onl;y after a little while (maybe after brakes have been used a few times). When I jumper the diagnostic port, I get error codes 21, 22, 23, and 24. These correspond to an ABS solenoid problem on each wheel ( 1 code per wheel, same error for each wheel).
I suspect something that is central to all 4, but don't know what is likely. ABS solenoid relay seems to work ok. When I jack up the car anr remove the wheels, the wheels turn freely.
Where should I be looking - ABS actuator, ECU, wiring harness? What tests (using simple tools) can I do to nail this down?