Dreaded abs light

[jcm325]

Hi, if anyone has any suggestions I would appreciate it.
Car stands for long periods of time, battery disconnected.
Trying to get her out for some use but I can't get MOT because of the abs light.
I've read the wiki and loads of posts online but I cannot cure the fault.
When I start the car the abs light comes on and stays on at all times, this apparently points to a system fault and not a wheel sensor fault, it normally happens when the car is jump started and it fries the over protection circuit in the abs relay.

Things I have done: replaced abs relay although I couldn't see anything wrong with my original / fuse wire intact
Replaced abs ecu with an ebay item , same part number and colour , could be a duff one?

Neither of these has resolved the issue, my next port of call are the x2 relays on top of abs pump? Or abs pump itself?

Reading online an alternator producing low voltage can cause this? Anyone have any experience of this? My regulator pack on my alternator was producing only 12v so I stretched the contacts and now it's producing 14v so I assume it's not that?
Also another online theory is si batteries, these were replaced probably 7 years ago so is it time to do these again ?

Any help or ideas would be appreciated and if anyone has the relays from on top of the abs pump please give me a shout.

Cheers

[Speedtouch]

Have you tried clouting the ABS pump with a rubber mallet or similar - maybe it has sticky valves. Could also be worth bleeding the brakes...