Why not get an auto-sparks to look at it?
It could be many things and guessing won't help until proper tests on the pump control circuit and relays have been done.
It's almost certainly not the ECU though.
I've never come across any connexion between the engine ECU and the power steering.
The alternator needs to charge for the pump to come in, but there's no link to the ABS - these have a VSS anyway.