how does the rear abs system work on a 03 Isuzu npr, I have a c0231 and c0235

Question

abs light is on, rear wheel speed sensors read 0mph on tech2, lab scope sensors and there is no wave pattern. replaced sensors no change, tone ring looks ok

Answer 1

C0231 Rear wheel speed sensor erratic

C0235 Rear wheel speed sensor open or grounded

There is a active wheel speed sensor which is  a magnetic sensor that generates its own A/C voltage, Then there is the passive one. The NPR are exclusive you can not use the GM or Isuzu wheel speed sensor, These have a common problem with the ABS unit,