2001 MERCEDES BENZ ML430 BATTERY KEEPS DRAINING

  • Tiny
  • lambo54
  • 2001 Mercedes Benz ML430

Electrical problem
2001 Mercedes Benz ML430 V8 All Wheel Drive Automatic

My car slowly dies (like a slow electrical leak). At first it will die if I don't drive it once a week, then once every 3 days, then once a day, but eventually it just dies. This happened last October so I replaced the battery -- obtained a brand new 6-year AC Delco battery. Went on vacation in January and when I came back the car was absolutely dead. It has, in the past, responded to a trickle-charger when this happened, and has been " jumpable" -- but not any more. I have also noticed that a small cylindrical object located immediately next to the battery will more often than not start whirring (motor sound) as soon as I connect the battery charger or jumper cables across the terminals, and I remember hearing this motor sound still running after the car was shut off back when it was still working. I've taken it to a shop which claimed that the battery held charge and that the engine didn't seem to be pulling more current than usual both on and off, but I then had to jump the damn thing to get it out of the parking lot! Any help would be absolutely appreciated!

Saturday, April 11th, 2009 AT 11:05 AM

3 Answers

  • Tiny
  • gfimotorcars
  • Expert
  • 681 posts

You have what is refered to as an amperage draw. This is a low current draw that is caused by a component or control unit not fully turning off. This is an issue not unheard of in this model but typically is seen more in the 203 model C Class. What is happening is once you turn the vehicle off a component is drawing low amps from the battery until it dies. This condition also will kill a battery, rendering it useless, over time as pulling the amps too low too many times ruins the battery cells. You will need to bring this to a shop you trust or I would recommend the dealership. The dealership has techs that have more than likely seen this and are versed on how to properly diagnosis it. Indepent shops will often times take shots in the dark as the electronics of a MB are often times too much for someone that has not been fully trained on the systems. This may take a lengthy diagnosis but without fixing the issue this problem will simply continue.

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Thursday, April 16th, 2009 AT 12:32 PM
  • Tiny
  • benzo01
  • Member

Hi lambo54; I am new to this site but I saw one of your posts and I Figured I would message you. I have a 2001 ML 430 and I am having the same problem with the battery drain that you had. I was wondering if you found out what the issue was, as I am getting frustrated with this problem. I hear the same humming sound on the passengers side next to the battery after shutting off. I was told that it might be the cps cooling fan which sometimes stays on after the turning off but disconnected and did not work. Can you help at all? Any information would be greatly appreciated.

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Monday, August 3rd, 2009 AT 8:40 PM
  • Tiny
  • Mab1963
  • Member

My 1999 ML430 also has a battery drainage issue. When the car is parked for more than 7 hours the battery becomes completely drained. I have a new battery and almost purchased an alternator (not the problem) and have not resolved the issue. Any suggestions?

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Monday, January 18th, 2016 AT 2:14 AM

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