Ok I got to get this figured out, I have a 05 MCS and last fall I had to replace the clutch. Dropped the subframe to make the repairs. After everything was buttoned up this is when I started having problems. It’s the electric power steering. If I turn the key to the on position the ps pump will slowly ramp up to 80% duty. Now keep in mind it did not do this till the subframe was removed so it’s got to be related. Now this weekend I finally replaced the ps pump with a Bosch reman and does the exact same thing. This should not work with the key in the accessor position. I also have a second R53 with 70k miles and does not do what this one is doing. So I get my Bentley manual out and shows the large 100A plug with the red wire power and brown going to ground. It it possible I have a ground issue? I have looked for a loose wire or anything out of the ordinary and nothing. Please help .

 

Does anybody have any ideas?

 

Bump!

 

That would be my first guess.
Confused a bit though:
then:
So is it happening in the first (ACC) position or the second (ON) position? Or what am I missing (probably your entire point) here?

Also, is the steering action otherwise okay once the car is running, i.e. no hesitation, intermittent loss of power assist etc?

 

I don't think it's a ground issue, but I do think there some wires that may be pinched that when you turn the key sends power to those pinched wires which activates the pump. Don't know where you should look, but I would trace back the wires from the pump to the power source..

 

Well after studying the wire schematics for the EHPS there a a yellow trigger wire that is in the 3pin plug connector that runs to the 3 pin plug to the alternator. It gets its signal when the engine is running from that alt wire and goes to the ps module. What’s a coincidence is when I was replacing the clutch I had the alternator rebuilt and the issue started right when it was all reassembled so now I’m wondering if they didn’t do something right in the alternator??

So I bought a new alternator and they told me I couldn’t return it if it was installed so I put the car is a slight front end service to give me room and was able to remove the power wire and plug from the alternator and plug it into the new one without mounting it. Turned the key to accessories and th ps pump started to run. Crap!! Put everything back together and was about to take the new alternator back when something came to mind... the alternator needs to be grounded through the block so I’m wondering if that could still be my problem??? I will be trying that tomorrow.