I have a strange problem with my mustang, and it is driving me crazy. I hope someone can help. Here it is. I have a 2007 mustang
gt with a 4.6L engine. I set the little screen in my dashboard to my mpg setting. I can turn my car off and walk away. When I return to my car, put the key in the ignition. I turn the key to the on position without starting the engine, the screen is still at the mpg. As soon as I start the engine, the screen goes to its default position of simply stating my mileage. The battery will also die within a month of the car not being driven. I have checked every single relay that has to do with the starting system; they are all ok. I have had the battery, alternator, and starter motor checked out. All are ok. I just replaced the ignition switch in the car, and that didn't help the problem either. I am out of ideas on how to fix this, and I am asking anyone who might have an idea of what I can check.