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Check battery alternator light came on. Batter was replaced…

Customer Question
Check battery alternator light came...
Check battery alternator light came on. Batter was replaced last year. Can I test the battery and alternator separate? Car idles rough when engine is cold. Advice?
Submitted: 2 years ago.Category: Mercedes
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Answered in 35 minutes by:
1/19/2016
Mercedes Mechanic: FIXITMAN, Master Technician replied 2 years ago
FIXITMAN
FIXITMAN, Master Technician
Category: Mercedes
Satisfied Customers: 17,611
Experience: ASE MASTER CERTIFIED, AA DEGREE DIESEL/AUTOMOTIVE
Verified

Hello, my name is Bobby. Thank you for the question. Can you tell me if you have a voltage meter to run you through some tests? If the battery light is on when the engine is running then chances are you have an alternator that is failing.

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Customer reply replied 2 years ago
I don't have any tools. I'm trying to get some direction before I go to the shop?
Mercedes Mechanic: FIXITMAN, Master Technician replied 2 years ago

Thanks for the response. If the car is starting fine then the battery should be just fine. The battery light coming on when the engine is running indicates a bad alternator. I would always check the battery connections first. If those are clean and tight then it is probably the alternator.

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