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Q: Dim stays on about 10 seconds, then go completely out. So I have to quickly switch back to brigt

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I have a 2005 Ford Mustang. My head lights work just fine on bright, but when I turn them to dim, they stay on about 10 seconds, then go completely out (while driving) so I have to quickly switch back to my brights.

My car has 120000 miles.
My car's transmission is unknown to me.

There are a couple of things this could be related to. First, you may want to have your alternator tested. This is your car’s onboard charging mechanism. If this is not operating correctly, it can lead to several problems, one of which you describe. Secondly, I would check the grounding and wiring harness to the lights themselves. This requires a bit of voltage testing with the use of a volt meter. If they are not getting the correct amount of voltage to them (which can be caused by old or corroded wiring, etc.), this can also lead to what you are describing. If you need help with this, I would recommend having an expert from YourMechanic come to your home or office to diagnose your lights and make the correct repair.

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