Super lost. My ABS module went out, so I unplugged the wires. I went to start the truck to see if the annoying buzzing sound had stopped. The truck battery is dead now so I have to charge it but the truck started doing this weirdest **** but only when I would turn the key off and take it out. A non stop buzzing noise from inside the truck along with the cab lights flickering off and on
https://share.icloud.com/photos/01egpXUf1FirL588487N0K9JQ

 

Put a full charge on the battery, see if the problem persists.

 

Does it behave normal when the ignition is turned on ? Try disconnecting the ignition switch. Otherwise start pulling fuses and relays when the truck is on the fritz and see when it goes away.