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Q: The battery light and the emergency brake light illuminate when I turn on the car. The car shakes when they are on.

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The emergency brake light and the battery light come on when I turn on the car and sometimes they don't turn off for a while. The car starts to shake and when I go over 3000 rmps they turn off but when the rmps go down they come back on again. This has been happening for a month.

My car has 17600 miles.
My car has an automatic transmission.

A: Hello and thank you for your question. Chec...

Hello and thank you for your question. Check your alternator for voltage at low idle and when the engine is at 3,000 rpm. It sounds like the alternator is not producing enough voltage at a low rpm. The battery light will come on when the alternator stops charging correctly (13.5 -14.7 volts), plus on some models, the brake light will come on indicating that there is no change in voltage.

For the issue you’ve described, I recommend replacing the alternator. If you need assistance with diagnosing the warning lights and servicing the alternator, then seek out a technician, as one from YourMechanic, that can assist you with your vehicle at your home or office.

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