I was driving to work this morning on the interstate this morning, and after 30 minutes me battery light and brake light were flickering at speeds 65-75 mph, When I got off the highway and reduced my speed to 55-60 mph this stopped, does anyone know what is going on and how to fix it. Thank you.
There may be a short or possibly a faulty cable connection.
I’d have a load test done on the charging system with an eye on the alternator and battery.
I would also check the condition of the belt and tensioner. This problem could be caused by a slipping belt.
~Michael
Those warning lights are in the alternator exciter circuit and when they start doing what you describe it means there is a problem with the alternator internally. Most likely a connection with the brushes is having trouble. Replacing the alternator will take care of this trouble.