I just had the power steering pump replaced on my '03 MCS. When I am parked and turning the steering wheel, I notice that the headlights dim a bit. Is this normal?

My understanding is that it's an electro-hydraulic system, and requires a good deal of energy to operate. When I'm parked at idle, the power steering is working the hardest, and the alternator is spinning the slowest. The headlights act more or less as resistors. The path of least resistance is through the power steering. Therefore, less energy passes through the headlights, causing them to dim.

Does that sound about right?

 

Yikes Turning steering wheel while sitting still throws heavy load on power steering pump putting heavier load on electrical system when it is making the least power and robbing juice from the headlights causing them to dim.
This is hard on tires and the P/S pump. Suggest you stop doing that unless you like replacing all those exensive items. Be happy and motor on

 

I assume you have Halogens (Xenon's can't really dim... once the ignitors fire and ignite the arc of plasma in the bulb they're just "On")...

My best guess would be either your alternator is taking a crap, or your battery is starting to show age. If you're car still has the OEM battery, depending on your climate, 5 years sounds like you're probably about ready for a new battery. Try running a load test on the alternator and seeing what it's putting out. Anything less than 13 volts with most of your electronics off is abnormal.

Most modern alternators produce pretty much the same power at idle as they do at redline, so low RPM's shouldn't be a factor. If that's the case then your alternator may be on it's way out.

 

I bought this mini 2 weeks ago from a dealer on the condition that the power steering pump was replaced. It has 27k and a clean carfax. The power steering pump was about to go. I picked it up last night and only turned the wheel back and forth as a test. I noticed the headlights dimming and thought I'd ask. Not something i intend to make a habit of.

I do have halogens. I'll check the battery and alternator this weekend. Thanks.

 

Power steering motor is a pretty big draw electrically so a slight dimming of the lights isn't anything to be concerned about. Still, no harm in testing it out.