Turn Signal relay location on a 2013 Petrbilt 386

Hopefully Goodysnap is still on this thread! I’m having the same issue as above where my left rear works but only have front left when I unhook one bulb, and no left on my trailer. I had a spare Cecu, chassis node and blinker switch. I tried all 3 and I’m really dreading having to tear into the main harness. Also noticed the numbers on the wires seem to change along the way!