I have had an annoying parasitic draw on my 01 ML430 FOR the past five years.I took it to an independent Mercedes shop they quoted me 8 hours labor to find it.After another dead battery I had enough and decided to locate the problem my self.First I disconnected the positive cable and installed ESI 306B 30 Amp Fuse Buddy ATC Tester.between the post and cable .Cycled the key on and off. Immediately after the key was off there was a parasitic draw of 600 milliamp. After about a minute the draw dropped to 300 milliamps where it stayed.I started pulling fuses until the draw dropped to zero.The fuse was F4 inside the right kick panel.I reconnected the battery and inserted the fuse amp tester into F4 and found a draw of 300 milliamp.According to the label on the kick panel this fuse controls the Tell cell module located under the right front seat.Disconnected the module and the draw dropped to zero.I ordered a used module from Ebay and installed it.Inserted the fuse amp tester into F4 and had a draw of 260 milliamps for about a minute and then dropped to zero.No more dead battery after two days of non use.

 

Thanks CLLARK1 for posting this! This started happening to me about 3 months ago with my wife's 03 E320. First I took out the radio fuse for awhile because that stayed on without the key on, but I think that was the "gateway module" or something like that. Then after replacing the main battery, the new one was dead in 24 hours! Then I replaced the battery in the front under the air cabin filter, just to go dead again in less then 24hrs. Today I decided to really look at this setupo and saw the little box in the trunk. After entering the parts number,it came up battery control module! Now reading your story Im going to check that out. Was there a way to check that module to see if it is infact defective? Thanks in advance

 

The way I knew the module was defective was buy pulling the fuse that supplied the Voice Control Module.When I pulled the fuse the amp draw dropped to zero.To verify I re installed the fuse and disconnected the module,again the amp draw dropped to zero.After replacing the module amp draw dropped to zero after about a minute as it was designed to.You need to check amperage drop at the battery.Make sure you close the latch on any door you have open.You should see the amps drop as the modules shut down.If after you still have a amp draw after a few minutes start pulling fuses.If the amp draw dropped after pulling a specific fuse,investigate which component it supplies.Locate the component and disconnect the component if again the amp draw drops you have likely located the problem. I read somewhere up to 80 milliamps is acceptable amperage draw for modern luxury cars.Someone on this thread suggest the Gateway module may control when the other modules shut down .https://mbworld.org/forums/e-class-w...ery-drain.html If when you pulled the fuse the battery did not go dead I would start there. Good luck

 

I've had a battery drain on my ML320 2000 for some time - temporarily 'solved' with a 20watt solar panel on the dashboard, plugged into to 12V power outlet.


I'd figured the 'cause' was an intermittent problem with the parking sensors - they and the reversing beeper would stop working in the rain, or when I'd washed the car. I thought initially it was an external fault, but now I realise it was a leak from the sunroof drain tube, going through the fuse box (right hand footwell, UK RHD). I'd fixed the lower end of the drain tube with heat shrink (three cheers to dbrace), although there didn't seem to be much sign of water compared the same problem on the left side of the car, but still had a leak/flood in the footwell, and was puzzled as to where the water was coming from, but had noticed a tiny amount of water in the fuse box, and later a drop or two of water that seemed to come from the inside of the front right hand side of the dashboard. I wondered if it might be the doorseal on the front slope of the door. Anyway, I took off the A-pillar trim to see if any water was coming from the top of the tube, but no evidence of water having been coming through in the quantity that had been filling up the footwell. However taking off the A-pillar stopped the footwell filling up with water and the parking sensors and reversing beeper now work when it is wet. I thought the water problem had mysteriously disappeared, until I realised why the back of my leg was getting wet.... Yes, must be the top end of the drain tube, so I rigged up a tray and some newspaper to collect the water, and that filled up quite quickly. Subsequently though, in spit of heavy rain, there has been no more water coming through - in must just depend on wind direction as to how much water collects on the roof. I suspect most water is going down the drain tube, but too much water leaks out the top.


Any way it is time to ease away the headlining and fix it properly, but also to check the fuses properly as per this post!


Cheers.