Got in the truck this morning, discovered that the left side speakers don't work. Went into the sound settings and moved the balance button around, nothing from the left side. Where should i start?

 

If you have forscan you can scan for codes
You could check if you have broken wires between the door and the pillar.
You could pull the door panel and swap the speaker with the other sides speaker, clear the codes to verify the speaker itself failed. If you do that and it's still not working on the left side you'll have to check wiring from the door the the audio control module, if that wiring is ok you probably have a failed module.

The easiest check would be swap the speaker with a good known one with the same impedancw clear the codes and see if it's working.

 

Actually i found an easier solution. Might have found the problem too. I normally connect the iphone with a usb cable, so it charges the phone at the same time. I pulled the plug and connected with bluetooth, works fine now. I’m thinking the cable is bad.

 

Huh, that's first I've heard about that. Sounds like you got it figured out. Good work.