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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 22807
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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ML430: I have q 2001 ML430. The problem is some source of power

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I have q 2001 ML430. The problem is some source of power drain. It will drain a fully charged (or new battery following unnecessary replacement) in 5 to 7 days to the point that it will not even try to crank, and lights are weak. The dealer has had the car in 3 times, and they have no idea what he problem is. What can I do to trace the source? Of course, no lights left on, no interior lights, doors close fully, etc.

Hello and welcome to JustAnswer!


What you'll need to do is a draw test.


Start by disconnecting one battery cable and setting up an ammeter in between the battery post and cable.


Also connect a jumper wire inline.


Press the lock button on the key fob and let the car sit for about ten minutes to time out.


Then come back and remove the jumper wire, the amount of current flowing will then be shown on the meter.


Anything over about 30-40mA is cause for concern. If draw is higher than that then you'll need to start removing fuses one at a time while watching the meter. If you can remove a fuse and the current flow drops then you can concentrate on components on that circuit.

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