Hi. I have a 2004 E20 4Matic. About 148K miles on it. Drove the car to the grocery store this morning, and upon returning, got the Visit Workshop/Battery Icon red light. Car starts, but makes a horrendous sound from the pulleys and belts. Roadside assistance came by and tested the voltage. Main batter is only 1-2 years old, but had corrosion on the anodes. 12.25 volts. On the aux battery, corrosion and 12.17 volts.

Recently, I thought I had an electrical issue (yes, I know I should have taken it to a shop sooner). When I would make my first stop at a traffic light, the car would shudder a bit. Once, when it was hot and I had the AC on, the car even stopped while idling and I had to restart the car. The roadside assistance tech said that something is draining power from either the aux battery (which, in turn, drains the main) or both batteries. I replaced the aux battery two years ago, but I suspect there is something in the car electrically that is affecting it.

The car, again, starts, but I can't drive it because the power steering is out and I don't want to have an accident getting it to the shop. So my questions are:

1. I know none of you can see my car, but is there any way of knowing what the problem is before I take it in? I'm hoping it's just the voltage regulator and not the entire alternator going bad.

2. Is there any way of restoring the power steering so that I can safely drive it to the shop without having to hire a tow truck? When I turn it on, sometimes I can drive with power steering, but only for a few seconds before it goes out (and returns a few seconds later). It's in a grocery store parking lot, so I left it there overnight rather than risk driving dangerously.

3. Are both voltages low (the car was running at the time)?

Thanks for any advice out there. Again, both main and aux batteries are less than 2 years old, so I am concerned there is a short draining my car.

 

Thanks. Before I do, does anyone else have any suggestions?

 

What does your power steering fluid look like? Where is the noise coming from? Do you even have a serpentine belt that's still driving components? What codes are being thrown?

 

Thanks for the reply. I am not with the car, so I don't know what codes are being given. The belts are on and they looked OK. I dont know if it's the alternator or voltage regulator or a short somewhere else. The noise was coming from the belts on the pulleys. No idea about power steering fluid, but I think it's OK.

Is there anything I can do to drive it rather than tow it?

 

If your power steering pump is siezed up it'll make quite a racket, your steering will be hard, and the alternator might not be spinning either.
I'd start by taking the belt off the pulleys and seeing what turns and what doesn't.
Other than that, What Plutoe Said.

 

Thanks for the replies. So when I went back to the car and touched the serpentine belt, it came off easily. So I got a tow truck and took it to a MB repair shop. Turns out the Accessory Bel Tensioner had broken apart. The belt itself was salvageable, but I decided to replace it as well. Alternator was fine and powered up. Cheap fix overall.

 

Still it is a good idea to check the power steering fluid. Real easy on M112 engine. Just open the hood and twist open the power steering fluid. Check the color and fill level. Low fluid and dirty fluid will kill a power steering pump.