Hello,
I own a 2003 E320...
I have a draw on the main battery when the car is left off overnight (Car doors will not even open in morning). We got a replacement battery with no success. Alternator tested fine, Diagonostics were run by electrical shock and has 2.2 AMP draw. Car runs absolutely fine after recharged, the only thing i've noticed is that the window functions which allow the window to go up entirely with one click (rather than holding) is disabled.

No mechanics thus far can figure out what specifically is draining the battery.

If anyone has any idea or experience with these issues any advice would be appreciated.

Thanks

 

Sounds like a ground draining the battery.

 

What does this actually mean? If there is any drain from the battery, it would end up from the battery positive pole to the ground. Do you mean some short circuit from worn out insulation? Shouldn't these blow a fuse.

 

Is it 2.2 A current draw when the car is in sleep? This is way too much, it should be less than 80 mA (your car probably has the alarm option, otherwise it should be below 40 mA).

Have you tried to unplug the memory seats connectors? Sometimes it is Comand, you really have to measure where the extra drain goes to.

 

The only way to find out the probs are to connect the car to diagnosis. A friend of mine has the same problems + that the alarm sets of during days, nights, driving and so on and they found out that the SAM module in the rear had given up. To that the seat memory modules had got fried so they also needed to be replaced. All that ended to a nice sum of $3000 in cost here in Sweden.

The reason for all this is to be connected to "jumper start" by another car or "start booster" when the battery is low according to MB. Those starting methods should be avoided.

.........**Thanks**.

 

All previous are accurate. However you can pull the fuses for the seats, over head panel and verify current draw. I had the same problem and the battery relay in the trunk mounted by the spart tire on the rear face was defective. There is a relay internally (I took my old one apart) that fails causing it not to switch when it should. This is a 10min part replacement and parts com has the part. Not cheap but cheap and MB don't belong in the same sentence.

 

I have the exact problem happening with my car. Did you ever find out what the problem was?

 

I have the same problem in my 2004 e320 wagon. We removed all the fuses from the seats and the problem continued. The dealer is stumped. I've taken it to two mechanics and it's always fine at the shop. There is no draw when they measure it overnight or for a week at a time, then I go home and it's dead the next day.

The problem *appears* to only happen in my garage so they are wondering if it could be a RF signal from my garage door opener or from my home that's causing the problem.

If it's a RF thing then would it be related to the Comand?

 

Interesting. I have 2003 E320CDi, and for a couple of months the battery convenience function warning has been showing most mornings for a few minutes, then clears. Then this morning, after 24hrs standing , the battery is flat as a pancake (well, enough to turn the lights on, but try to crank and all the dash goes, clock resets etc).
Possibly a short/drain on the battery. Possibly some relay stuck (that rear one in the boot by the battery?).
Currently charging the 'original' MB battery and will see if it reoccurs.

 

Battery charged and replaced, but still warning about no convenience functions, so I think a new battery is a good idea.
Also noticed the SBC Hold brake not working and causes ESP fault to be displayed if attempted. ESP seems ok if don't attempt to use SBC.
Need to get that looked at.
Not sure if linked to battery drain. Potentially I left parking light on or something - I had been playing with the lights.

 

Take keys out of ignition, then push the radio power button. If the radio comes on then I think it's your audio gateway module. take out fuse #6 in the trunk fusebox and see if your battery dies the next morning. That's what I had to do for awile. But this is just one of the many things that could cause battery drain.

 

I would wait at least three minutes for the gateway to go to sleep before seeing if the radio will power on. When you first remove the key, whatever is connected to the gateway will stay powered until it goes to sleep.
Mike T.

 

I have the same vehicle and same problem and can not locate the issue.

 

My battery drained overnight. When I looked at the repair manual CD from Mercedes, it said to put a high current draw ammeter between the battery negative and the body ground. That is, set a multimeter to 20 amp range and measure the current draw on the battery.

Then depending on the current draw, the CD said the cause is something in a short list. As I recall for 60 mA (milliamperes) to 140 mA, it might be a trailer hitch wiring problem, a radio relay #4, or a fuse in the hat trick. Ok, maybe I don't recall the list at all but it was a list and there was a list for each range of current draws.

The CD is not great to use but it does have a load of info when you are troubleshooting and since you order through MB or at the dealer, it is legit.

 

It's the power seat module (under the seat. Disconnect and the problem will be gone. (Did cost me $330.00 in diagnostics.)

 

It's the power seat control unit (under the seat). Disconnect them and the problem will be gone.

 

I had the same thing years ago. A simple but tedious test is to put an amp meter on the battery. Then start pulling fuses until the current flow drops.

Mine was an aftermarket CD changer. It worked just fine but when I unplugged it, the draw ended and the battery stopped draining. If I was driving it every day, I would leave it plugged in but when I left it for a business trip, I would unplug the changer. FWIW, The car was a 1992 300TE wagon.

Good luck,
Peter

 

BTW, as I recall, the current flow with the changer was 240 mA and more like 20 mA without.

 

anyone still has any solid solution on this? so i replaced both battery and BCM.. still having a battery drain overnight.. i have not disconnected the seat relay module to test it out (next step to perform).. i read about the radio turning on after you remove the keys on the ignition but did not wait enough time (another test i need to do) .. anyone know how long i have to wait to test out if the radio will turn on after removing the keys on the ignition?

 

update: went to my local indie and he told me to change the battery to OEM from mercedes, he advise me that battery from other company are not good and do not have enough reserve and the reason the battery is draining to fast.. So i went to Mercedes to buy OEM battery and i have not have problem for 3 days now.. will continue to update once i have more data/information.

 

@pinoi Ryder...
any updates

 

any updates? I'm having the same issue I bought a new battery from advance auto a group size 49 and my battery keeps draining after 5 days .alternator is good .

 

A simple but tedious test is to put an amp meter on the battery. Typically, this is the 10 amp setting and one cable is on the battery and the other on the battery wire (so all the current goes through the amp meter).

Then start pulling fuses until the current flow drops. BTW, as I recall, the current flow with my problem was 240 mA and more like 20 mA without.

Peter

 

I too have had and now again have this issue. Last time it cost $400 to diagnose from MB was the drivers seat module. I ended up buying one from Amazon for under $175. Dealer wanted $700 including diagnostic fee.

A few months ago, my radio started doing random restarts when the outside temp was <55F. A few weeks ago that changed from random restarts to hearing a buzzing noise followed by the audio going out for 10-30 seconds. I also noticed that in the mornings, my battery was drained and one 2 occasions, the car wouldn't start. Yesterday I unplugged fuse #6 hoping it was the messed up radio that was causing the drain, however, my battery was dead again this morning. Tonight I'm going to test the amp pull and also disconnect the battery to see if the battery is draining on it's own. I just got the battery early last year so I doubt that's the cause but would be happy if it is, since it's still under warranty.

Does anyone have a list of what the other fuses do? And just to clarify, if I pulled fuse #6 (radio), is there anything else from the radio that would pull current from the battery?


here's a link to the seat module (drivers side) https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

 

just notice it the other day i have indicator again for convinient functions not available.. my car starts good.. only getting the malfunction notice.. this is after 12 hours of park. then this morning i got the same notice..

i have not done the test yet for draw drain.. i will check the seat memory and remove the fuse to see if that is the cause..