What have you actually done so far?
In all honesty many people have been on the forum many times in the past, changed the battery, changed the alternator, changed wiring, earths, paid out hundreds in diagnostic fees to someone but ultimately still ended up stumping up for a new electric power steering unit, these days they are not that expensive.
£50 on a registered copy of
MultiECUScan could quickly give you the cause of the light and pin point you to what needs doing rather than a bits swapping approach.
A multimeter will only tell you how many volts the alternator is producing it won’t tell you if you’re getting the right current and to be fair with a new battery you shouldn’t get power problems anyway as when the steering wants more power than the battery can provide then the battery will take over. If it were doing that all the time the battery would become quickly depleted, you’d have problems starting the car. The lights would dim if turning the steering lock to lock and the power steering would cut out eventually.
Don’t waste time hoping for a lesser problem that likely isn’t there. Also don’t mess about with the steering, at least one member on here had the steering cut out while driving resulting in a nasty accident and a written off car.
