I've been having an issue with my passenger tail light ever since I've had the truck. When I press the brake, the turn signal bulb illuminates, as well. Checked it with the multimeter, and it's getting full power when the brake pedal is pressed. None of the front lights are affected, and the driver side tail light has no issues. Any ideas? Or is this one of those issues that involves me following the wiring harness all the way to the front of the truck?

 

Here's an update. Not sure if it's a big deal, and you can see in the video, but my brake circuit is around .50v lower than the turn signal.

 

Found the issue, after I finally had time to tear into it. Some jack wagon who owned it before me put a jumper between the tail light turn signal, and the trailer turn signal wiring. The trailer turn is also the trailer brake, so there's where the issue came in. No idea why they did that since all the trailer lights still work after removing the jumper, but at least I found and fixed the problem.