So I noticed the other day that I had a lamp out issue on my truck and when I activate the blinker all I get is a fast blink and none of my turn signals except my right rear turn signal worked. I replaced all of the turn signal bulbs to no avail, when changing my bulbs in my left tail light I noticed that the plastic was slightly melted against the bulb. I replaced the assembly and nothing has changed, none of my turn signals except my right rear flash but all of the bulbs light up when the lights are on. Any idea what may be causing this? I am extremely clueless when it comes to electrical problems so any help would be appreciated!

 

Check the brake lamp in both sides, when the plastic base melts you can get intermittent contact. Very common issue.

P.S. Multi-function switch (Stalk) can give some weird gremlins too.

 

Just happened to me. It is a corroded circuit in your fuse box (Integrated power module). Had the same exact issue only turn signal that worked was my right rear. Including hazards.

It can be dismantled and fixed, but you have to be very careful. Dealer will tell you you need to replace it for hundreds of dollars. But it can be fixed rather easily once you get the fuse box apart. If you want to try it let me know I can send you links to two videos.