Car speedo in op, vehicle speed ok in abs live data, but missing from engine live data.

Dived straight in and started looking for break in usual grey wire in loom on N/S/F wing, after not finding any problems I decided to look a little deeper.

When testing with the vehicle running in gear on lift,the grey wire from pin 12 on ecu (according to autodata, from vehicle speed sensor) has +ve 12v, with no square wave.

My question is do all 4 wheels need to be turning to get a speed signal? and which wires on abs unit produce the signal, as I dont seem to have a signal here.

Autodata and vivid both list a wire from vehicle speed sensor, but I assume this must come from abs ecu.