Battery drains over night?

2003 MERCEDES BENZ E320

168,000 MILES • 6 CYL • AUTOMATIC

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Hi, every morning I have to jump my car to start. i couldn't figure out what the issue was until i saw my cars fog lights and rear lights would blink intermittently, sometimes when i turn the radio on it gets stuck on the "Mercedes Benz" logo and then it will turn on by itself, the inner flash lights won't turn on for a while until the car has run for some times, the radio also gives static noise intermittently. i think it's the alarm sign module but i could be wrong.

Thanks in advance.

Jan 14, 2023 at 8:11 PM

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It sounds like you may have a weak battery, I would follow this guide to load test the battery

https://www.2carpros.com/articles/car-battery-load-test

If the voltage of the battery is low, it will cause the systems to malfunction. If the battery is new or tests good, I have seen the battery in the alarm module leak and cause all kinds of weird problems, check out this video of the job being done in a similar merc:

https://youtu.be/3S0Ns3O3ULA

I have also seen the front or rear SAM module go out causing strange problems as well but to be sure we should do a CAN scan which is easy, you can get a CAN scanner (Controller Area Network) from Amazon from about $32.00 here is a video to show you how.

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Amazon CAN scanner Link.

https://amzn.to/3G7mpFP

Check out the images (below). Please let us know what you find. We are interested to see what it is.

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Jan 15, 2023 at 11:10 AM