Hey, I have a 95 C280 and I have been having a problem with my battery. As long as I drive the car everyday, it will start fine, but once I rest it for a couple of days (now just one day) the battery dies. I am 95% sure the alternator is fine. and it has to be a short somewhere because I have changed the battery like 3 times (thank God for Advantage Auto Parts Warranties) and it still happens. Can anyone tell me the process of trying to figure out where this battery draw is coming from? Bringing it in to my mecanic is my last option since he charges so much. Thanks guys...

 

well you can start by performing a draw test. put a test light between the neg. terminal and the neg cable(yes this means disconnecting it from the post) the light should will be on bright if there is a draw. if the light is on bright start pulling fuses till the light goes out then there is your problem.


just a hint start by disconnecting your cd player and your power antenna

 

got electric seat adjustment?

known problem is seat control module.

 

can you tell more of seat adjustment control killing batt?

 

Dont pull fuses! This can reset a control unit causing the draw to go away for a short time and then come back. Also pulling fuses wakes up the car. It can take up to 30 min for the electrical system to fall back asleep. 30 min for every fuse is a waist of time!!

 

So how would I go about trying to figure out the problem??
Also, this is the same exact way two mechanics told me they would figure out the problem.....

 

If you dont want to take it to a dealer then invest in an "Amp Clamp". Measures the amount of amps flowing through your wires without opening the circuit. A draw should not go over then about .050mA. In your case is sounds like you might have around a 1 amp draw.

If you dont want to invest in this, then just disconnect your seat control units one at a time. These are common problems on your model car. Both of them could be bad!

 

Appreciate it MBZ Tech.....Also, while I was going through the fuses, two things that stood out were #12 (instrument cluster/stop lamp/lamp monitoring system) has a 20amp fuse in it. The diagram calls for a 10amp fuse, and #10, supposed to be vacant but has a 7.5 amp fuse in it. Can either of these cause potential problems??
Also, exactly what is a test lamp? Is it something that Ill have to purchase, or is it a small light bulb w/ two wires attached to it? trying to save some money here, if I cannot figure out the problem in a few days I'll just have to bring it in to the mechanic. But thanks again guys.

 

I would replace the fuse with what its suppose to have. The Vacant spot is for extra fuses. I wouldnt worry about that one. Thats what a test light is. The most common ones look like a screw driver with a light bulb in the handle and a wire coming out from the end.