Speed sensor Rear

[Auldcodger]

R1200rt 2006 ABS has been deleted,
Speedo bounces when bike is rolling, the trip counter increases at an erratic rate.
If the bike is stationary the trip counter stays stead until rear wheel is moved then it starts increasing rapidly also mileage increases accordingly.
if the rear abs/speed sensor is disconnected and the bike started up then all values for the trip and mileage stay as is.
the fault only occurs when the speed sensor is connected. I have replaced the rear sensor with the front one (is this viable) and the issue still occurs.
The ZFE has been changed so im thinking that it may be an issue with the ABS control module.
Anyone got any suggestions :-/