Electrical System Problem
 

2011 Shelby GT 500, Started intermittently but has become constant, start car and get many errors, radio and AC don't work or cycle on and off, backup lights and brake lights don't work, turn signal doesn't work on instrument panel, tire sensor on. Thought was leak issue but no water leaks. Car runs fine. Have recently seen some other blogs with issue. Any suggestions are appreciated.

Many strange things start happening when the battery starts going bad.

yeah I would also suspect the battery first . . . if it is about 3 years old or more, I'd probably just get a new one as the first troubleshooting step . . . unless I was really strapped for cash, which you probably aren't, considering you have a GT500

Definitely, keep an eye on the alternator/charging system as well. My first mustang (2005) started having really odd issues like this and the alternator died shortly after, ruining the battery as well.

The 2009 and earlier cars had a lot of problems with the alternators; the 2010 and later alternators are much improved, so hopefully the alternator is OK in the OP's 2011

I agree with the others, start with you battery.

Thanks everyone, but replaced battery recently and it did not change anything. In looking at NHTSA site and complaints on 2011 Mustangs there is a 2017 complaint by an individual in Missouri along the exact same lines as the issues I am having. My thoughts are that I have had a moisture buildup that has caused some electrical component to short.