As I was driving, about 80-85 mph on the Interstate, as I normally do. And I started to hear a knocking noise from the engine bay, when all of my accessory electronics, after market touch screen radio most notably, went black and the noise turned very metallic. I didn't have anywhere to pull over so I kept driving and it seemed to heal itself. Once I was able to pull over, I checked it out. It made no strange noise and started back up like a champ as usual. Any thoughts, I'd like to fix it before it turns into a more serious problem. Thanks.
​​​​​​

 

Belt tensioner, idler pulley, alternator, just to name a few starting places.