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Dan, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 1355
Experience:  Dealer Auto Technician
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Battery was dead. I charged it fully but the car won't

Customer Question

Battery was dead. I charged it fully but the car won't start. No lights are on
JA: Did you test the battery with a voltmeter? And have you ever changed one before?
Customer: I have a battery charger that indicates its fully charged
JA: What is the model/year of your Mercedes?
Customer: 2009 ML350
JA: Are you fixing your ML350 yourself? What have you tried so far?
Customer: For now just bought the battery charger and charged it
JA: Anything else you want the mechanic to know before I connect you?
Customer: I suspect the battery was drained through the USB lighter adapter that was left in the car overnight. Also I just bought this car a week ago.
Submitted: 1 month ago.
Category: Mercedes
Expert:  Dan replied 1 month ago.

Hello my name is***** am an ASE Master Technician and I am glad to help you out with your question.

Expert:  Dan replied 1 month ago.

Check the main fuse under the right front seat.

Expert:  Dan replied 1 month ago.

Here is a diagram of the power distribution.

Expert:  Dan replied 1 month ago.

Please reply to this if you need more help and we can continue this conversation at no extra charge. This does not have to be my only answer. If you are satisfied with my service, please rate at the top of the screen. Rating does not close out your question. Remember, sometimes it is difficult to completely diagnose your vehicle without being there, but I will try to give you the best answer I can. Hoping to be giving you 5 star service.


Customer: replied 1 month ago.
Hi Dan
Expert:  Dan replied 1 month ago.

Let me know what you think and if you need more help please reply.

Customer: replied 1 month ago.
with the main fuse - what can I do if I find it?
Expert:  Dan replied 1 month ago.

See if it is blown, if it is replace it.

Customer: replied 1 month ago.
OK the main fuse is located under the passenger front seat. How would I know that it has blown?
Is that something generic I can obtain or it needs to be a special Mercedes fuse?
Expert:  Dan replied 1 month ago.

You can look at it and see through the window if is it blown. You should be able to get one at any auto parts store.

Customer: replied 1 month ago.
Is that a common problem when you drain/charge battery?
Expert:  Dan replied 1 month ago.

Its common if you charge the battery and still have no power to anything in the vehicle.

Customer: replied 1 month ago.
OK, just looking for this on the net. It shows that the fuse box is located under the hood? is that different than the one under the passenger seat?
Customer: replied 1 month ago.
See attached
Expert:  Dan replied 1 month ago.

My service manual wiring diagram show it under the seat.

Customer: replied 1 month ago.
Also, which fuse (based on the diagram) could be responsible for engine start failure?
Expert:  Dan replied 1 month ago.

The starter fuse is under the hood, here is another diagram.

Customer: replied 1 month ago.
Thanks. So its either fuse 105 or fuse 122
Expert:  Dan replied 1 month ago.

Your welcome.

Customer: replied 1 month ago.
Unfortunately looks like all fuses are fine
Expert:  Dan replied 1 month ago.

Have you tried to jump start it?

Customer: replied 1 month ago.
No - I haven't. Thought charging would be safer
Expert:  Dan replied 1 month ago.

I would try to jump start and see if it will start.

Expert:  Dan replied 1 month ago.

Hello again Dan here,

I am contacting you because the post has not been closed or rated.

This question is coming up on 7 days which means it will time out and close.

You have already paid to get this question answered, but you have not rated.

Let me help some more. Is there anything else I can help you with?

If I did not give you 5 star service, please let me know what I missed.


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