i had to test mine at the sensor only way i got a reading was when it was set to milli volts on the meter

and in the end i gave up as i couldnt work out which one needed a seensor
so changed the two fronts and was still the same

so just cleaned the earths up on the sensors and sanded the hub down to get rid of surface rust

put it all back together and job done abs working again and no probs since