Light sensor warning and the battery alternator check turns on when accelerating

Tiny
DIONIS
  • MEMBER
  • 2005 MERCEDES BENZ C220
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 317,000 MILES
Hi, whenever I go full throttle I get the light sensor warning and the battery alternator check. When I get the first warning it just turns off my radio then it comes back again, but when I get the battery alternator warning I can't shift, use turn signals, windows or anything. When I measured the electricity, it came back 20V. What do I do? All those started when my right rear-view mirror got hit and broke the signal light there.
Sunday, March 27th, 2022 AT 7:10 AM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

Where are you getting a 20v reading? That is a serious overcharging issue and likely the result of a voltage regulator issue.

Do me a favor. Follow the directions in this link and let me know the results. Also, if you are certain, it is producing 20v, I would recommend waiting until it is fixed before using it. That much voltage can damage other components.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I'm not sure where you are located, but this model (C220) isn't listed in my manual, so it is likely not offered in the US. My manual starts with a C230.

Let me know the results of the test.

Take care,

Joe
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Sunday, March 27th, 2022 AT 7:34 PM

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