Hi Everyone,

I'm new to this site and want to thank everyone in advance for contributing to the wealth of knowledge contained here.

I recently purchase a 2002 S500 with around 115,000 miles. Over the last several weeks I have been experiencing a plethora of electrical problems which are confusing me to an extent that only electrical problem are capable of.

The problems will come and then go away for apparently no reason only to come back worse and afflicting more of the vehicle's functions. Here's an attempt at a little breakdown of what I'm experiencing here:

1.)When I bought the car the following things were wrong:
-The key was stuck in the ignition
-The left break light and right rear running light were out(Was told it was the houstings)
-Neither the hazard lights or any of those to the left or right of it will work.
-The left front passanger window won't move.
-..........

2.)Beginning about 5 weeks ago my car would not want to start after sitting overnight about once or twice a week. Took it to the auto store and they said the battery was fine and only a year old but also that it was too small. He didn't seem to think this was a big issue however so I let it go. In retrospect it looks as if maybe I should have upgraded.

3.)3 weeks ago.....Car will still not start some mornings and often will not start even after sitting for only several hours. Usually will still start instantly upon hooking it up for a jump, however. Sometimes though it will be completely drained.

4.)2 weeks ago.....Car begins doing weird things upon starting it up and while driving it. One of the headlights will go out(the right I believe). The windshield wipers will not start sometimes and even more often will not turn off. It did this for about 3 days then was fine for a week. Started okay and lights/wipers were fine.

5.)Beginning yesterday, the wipers and headlights began acting up again and now the air ride is sunk all the way. Almost sitting ontop of the tires. This has previously happened when in very cold weather for several days without starting but not like this. It won't raise no matter how long it sits.

Any thoughts?

Thanks guys!

 

Have you had the alternator tested yet, and have you taken voltage readings at the battery terminals with the car off, and with the car idling? You should be seeing around 12.6v at the battery with the engine off and 13.6 or so with the engine at idle. I think 2002 was still a year where they were using alternators with replaceable voltage regulators; the regulators have wearable brushes just like electric motor brushes, and when they wear down the regulator loses contact with the windings in the alternator and will result in low output until they fail completely. Easy enough to replace and inexpensive.

What kind of battery is in the car now? Is it an MB battery or an off-brand? If it's not a genuine MB battery, it should still be a sealed battery, or better, an AGM. If it's a conventional lead acid battery that someone has thrown in there, I'd replace it due to the potential safety issues associated with flammable gasses venting into the trunk.