So I have an interesting problem with my R53. I flushed and changed the coolant the other day and took the car for a test drive. it drove great, but I stopped for a snow cone, and when I started it back up, the battery light stayed on and my power steering was gone.

when I had it idling for the coolant change, I thought the power steering pump was being a bit noisier than usual, and this car hasn't been in for the recall yet.

I changed the battery out, and the problem is still there. I had the new battery tested at autozone and it read something like 700amps, but 10.8-11 volts. I'm also getting about 11 volts on my obd reader. My multimeter is MIA.

I went ahead and ordered a new alternator, but I'm not 100% on my diagnosis. Does anybody have any opinions/experience/advice on ways to confirm it's the alternator?

I've been through the power steering pump recall with another R53, and when it failed it was no battery light and it kind of cut in and out for a while before it finally went kaput.

 

Very likely a kaputt'ed (German English or English German) alternator which function is a prerequisite for PS funtionality.

 

Racing guy - I hooked my DVM up to the power outlet in the center console, so I could monitor voltage.

I found that the alternator doesn't kick in upon initial start, but does after the engine revs up.

I would certainly measure system voltage before you buy a new alternator.

Maybe you disturbed a ground wire during your coolant change.