With ignition off, unplug the connections at the ABS Module and the Wheel Sensor. With a meter, check the continuity of the White/Green wire from module end to sensor end. Its resistance should be less than 5 ohms. More indicates a break or damage.

Reconnect module connection, then at the sensor end, check the voltage between the White/Green wire and ground. Anything above 3v indicates a short to a live source.

Then at the sensor end measure the resistance from the White/Green wire to ground. If less than 10k ohms, a short to ground is indicated.

Repeat those three tests on the Brown/Green wire.

Hopefully, one of those tests will reveal a fault but even then it might take a bit of finding! Any chance you damaged part of the wiring harness with your starter motor change?

 

ABS problem solved. Replaced the ABS module and that's it. At the end you were right. It was an electronic problem after all. Thanks for all your help Astromorg.