I have a 2001 S500 that I bought in Feb. 2005. I am on my 3rd battery. If I let the car sit for a couple of days the battery runs down and will not turnover without jump-starting it. Any ideas what may be causing this? Any easy fixes without going through a total electrical/electronic system check and trouble-shooting? I'm afraid it may be some kind of onboard computer drain which can be expensive. The car has 52,000 miles without an extended warranty. Thank you in advance for your help.

 

it got battery drain.

it can be eis, ocp, ucp, tel module, etc.

have it fixed.

 

Thank you Sleepwalker. Should I have it checked at a dealer or independent Merdedes shop?

 

the dealer can easily detect it because they are used to it. better take it there because if it happens to be the EIS, only them can replace it.

 

If you want to try to isolate it, you can hook up your voltmeter to read amps and put it inline on your battery connection. You should see how much current the faulty system is drawing. Then you can pull fuses one by one while watching the current on the meter and when you hit the system that has the fault, you will notice a significant difference in the current draw. Then you can try to isolate which component/system is giving you problems.

I would get this fixed ASAP, as you do not want to keep jump starting it. It's NOT good for the electronics and you could smoke something else in the process.

Hope this helps

 

Thank you Sleepwalker and SL600 Cruzin. I'll try the ampmeter test one fuse at a time to try to locate which circuit is drawing the power. If this doesn't pan out, I'll take it to my local MB dealer to diagnose the problem.

 

Napster,

So what turned out to be the problem of your 2001 s500? I am currently having the same problem with my 1999 s320 w220 body. Please post your solution to the problem. Thanks.

 

Hello Emi and welcome to the mercedesforum. Well, in response to your question, I bought a new battery again and took the S500 to an independent MB shop who sent the car to an auto electric shop. The auto electric shop did a complete check of the electrical/electronics and could not identify the source of the battery drain. They said it was an intermittent problem and asked that I take the car back the next time the battery drains down. I ended up installing a battery cut-off switch which I attached to the negative battery cable in the trunk. I use the cut-off switch when I plan to not drive the car for a few days. So far, so good. A little inconvenient and annoying, having to resort to something like this on an expensive, luxury car. Hope you have better luck in fixing your battery drain. The Napster

 

do you have an aftermarket sound system? or any thing electically after market?

 

No, there isn't anything aftermaket. Everything is stock factory including the options that are included with the AMG sport package like navigation, active body control, airmatic suspension, parking sensors, etc. Please let me know once you identify the source of your battery drain. Good luck.