Cant read ABS fault code

Hi
im getting the anti-lock light, and it stays on constanly.

I have tried using a analog multimeter to check the fault code, but there is no reading. What could be causing this?

I have checked all the abs speed sensors and they look good.
I have tried with a different ABS ECU

Could there be a short somewhere preventing me to get a read using the test port under the steering wheel on driver side?