All was fairly well with our 2002 C240 until last month when we had to have the catalytic converters replaced (and did the spark plugs and front brakes too). A costly visit to the mechanic.

Anyway, last week the car was dead, so we figured obviously it was the 6-yr old battery. The car had been driven every day until last month when hubby went on extended vacation and it sat idle a week....hence a dead battery. Well, we changed the battery (replaced with same MB battery) and it was fine until it sat idle again--this time for only 4 days. Dead car again.....nothing, nada.

So, replacing the battery again obviously isn't going to cure it. Can we jump start this battery? I've read conflicting thoughts on this. We need to get it to the mechanic.

Anyone know a common, likely scenario that is all of the sudden causing this?

We were to the point of trading it in and getting a newer model, but figured after $4000 work on it last month that we'd keep it another year until it paid for itself.....but now, faced with yet another costly repair....AAARRRGH!

Thanks!
Tracey

 

Upgrade fuse# 52 in frontSAM from 15A to 20Amp

Do NOT jump start the car,... it could damage the front SAM,... very expensive! Read your owner's manual. There a ways to try to jumpstart without a car that's NOT running,... but still need to be very careful. I would recommend using a "trickle charger",... the OEM MB trickle charger are made by CTek,...

Do you have power seats? If so, it's likely draining your car battery,.... disconnect your power seats,... plug under the seats. Search for the power seat module draining car battery power,.... it's common,... permanent fix is in that thread.

 

Thanks for the reply. I'm afraid hubby doesn't feel qualified to start messing with the innards of the car (fuses, etc.) unless he had a good written guide to follow.

I just realized we actually have a trickle charger, we'll give it a try. Hate the thought of having it towed to the mechanic, so I hope we get it running. I read on here somewhere to use the trickle charger with another battery also connected to the dead one via jumper cables (but with car OFF) to give it a slight charge to keep the smart charger from "knowing" the battery was completely dead--something like that.

Thanks again,
Tracey

 

When using the trickle charger,.... follow in the instructions in your owner's manual,... not what was said by some online idiot, myself included!

I assume hubby can manage to unplug the power seats (plug is under the seats),... do it with the key OUT of ignition.

You can go into dyno-mode to get a voltage reading on your car battery
Basically, 12.7V is 100%, 12.5V is 90%,.... 12.0V is 50%,....

 

Ha, hubby can't so much as replace a fuse and his wife is posting in the forum.
Kudo's to the wife!

Ooooo! Later version coding gives more info in Dyno mode.
My 2002 only gives you the version coding, the oil level, and Dyno on and off.
Doesn't show voltage or VIN. AND you gotta hold the damn button for like 40 seconds to get the beep, and then push one of the buttons on the left side of the wheel with the sheets of paper, I forget which ones.
So Tracey, this video may not apply to you.
Gotta use a voltmeter.

Tracey my car died completely recently from the big rain we had, then came back to life after things dried out. But my battery was still good, I Measured the voltage.

If you have electric seats this is the likely culprit with a new battery.

New seat modules cost like 500 each, but there's an inexpensive fix here on the forum, with detailed instruction that perhaps you or hubby can follow. Just search on power seat module or something.

 

Thanks, C230 Sport coup.

We've been busy, so the car still sits in the drive. We did buy a jump starter that a car friend told us to get (and it's charging now--we'll try it tomorrow). I'm hoping we can get it started and drive it to our import mechanic for diagnosing. I don't want to spend $500 per seat (yikes!), so I have already looked at the "fix". If hubby doesn't feel up to the task, maybe we can get the mechanic to perform it if that ends up being our problem.

Thanks again!
Tracey

 

Hooked up the jump starter today and nothing. The key won't even turn--no dash lights, etc.

Is it just coincidence, or could the work done on it only 2 weeks prior to first dead battery maybe have done something to it? We had 2 cats replaced along with spark plugs, front brakes. Wish we'd have traded it in before then like we discussed.

Thanks.

 

Just an update to close out the thread......

It WAS the seat module. We found a Mercedes-trained mechanic who knows about the "fix" and will do it for us at our request....which I wouldn't have know about at all if not for this forum--so thank you! You saved us some bucks!

Tracey