2002 C70 T5 - abs fault but no lights / fault codes

[pawvolvo]

Has anyone come across this before? I have a C70 that is showing no warning lights on the instrument panel, which the mechanic tells me is showing no fault codes and yet the abs pump is clearly firing on light brake application. You feel it as pulsing coming back through the pedal and hear the sound - makes the brakes feel horrible. At its worst when light braking from 40 mph.

I took out the abs fuse and the problem went away but 3 lights came on on the dash. Abs works normally under heavy braking.

My next step is to take the abs ecu out and send it away for repair. Just worried I could be wasting my time and money since there are no error codes.

Any thought?