2011 f350 left rear turn and brake light stopped workig

either bulb..or turn signal switch..

New switch. No power to the left rear turn or brake light. I do have tail light. Fuses are good. Left turn relay under hood has power on one socket but won't flash on the other

2011, Just replace the bulb, turn and break light are on the same filament. Probably a 2 filament bulb, one for tail light, and the other for the break, blinker light.

So you checked for power at the socket with a test light for the break light? And how about the wire running to the socket?

There is no power to the light other than tail light

Then I would try replacing the break relay, and the turn signal relay. 2011 doubt that there would be a wiring issue. Check them fuses for these circuits also.

I don't think there are relays. I heard it needs a dealer reset?

Well I haven't heard of that, but anything is possible. I just got done looking for break & turn-signal relays & do not see any for your truck. The only thing I had seen would be a hazard & turn signal flasher, break light switch, turn signal switch. So something new for me to brush up on. I would figure there is something simple to correct this. At this point the thing I would do is trace wires and look at connections. Sorry.

Now the right went out. Have the dealership put a new smart junction box in the fix the left one about seven months ago. Now the right ones out LOL

How much did it cost to have a smart junction box replaced?