Huskycamo

I know that the front ones are as I replaced them. Not sure about the back ones

Hi everyone. Bit at wits end at the moment with my BA ute ABS Braking system. When travelling under 20 kms and begin braking ABS kicks in and I have vibration through the pedal. I have had new ball joints. Fitted front abs sensors, swapped abs module side of abs unit front hubs feel fine. All wheel speed sensors read ok through scan tool with no codes stores. Could a bad rotar be tripping the system on? Bad battery? Any suggestions I could do with help/ Regards