Battery warning light turning on?

ABOOTHMAN

MEMBER
2005 MERCEDES BENZ C200
4 CYL
TURBO
2WD
AUTOMATIC
350,000 MILES

Hi dear,

I had battery alternator warning light, and it was voltage regulator problem. I couldn’t find one, so I bought a new alternator. Two weeks after installing the new one the warning light comes on for seconds and sometime for minutes and goes off. It does it three or four times daily.
I hope I was clear thank you.

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4 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

Yep, it sounds like you have a defective alternator. Can I ask which brand it is? To help confirm the issue of when the warning light is on let's use a voltmeter is see if it charging or not?

This guide can help:

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

Here is the correct way to replace the alternator in case you need it. Check out the images (below). Please let us know how it goes.

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Friday, October 27th, 2023 AT 5:10 PM

ABOOTHMAN

MEMBER
8 POSTS

Hi there, thanks for replying. The alternator brand is Bosch. I’ll measure the voltage when the light comes on and tell you.
Thanks

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Sunday, October 29th, 2023 AT 11:37 AM

ABOOTHMAN

MEMBER
8 POSTS

Hi dear,

Thank you very much.
I was waiting for the warning light to go on but it goes off straightaway so I couldn’t measure the voltage when the warning light is on. But I found the cause of the problem was the lower coolant hose which is above the alternator was leaking and dripping on the alternator causing the light to goes on and off. Fixed the leak and the problem has gone.

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Sunday, November 5th, 2023 AT 1:32 AM

KEN L