[Hook'em_Horns!]

Originally Posted by lmao43

ok ill keep looking

Standing on the left side looking right, in the top left corner are 3 in a row, 15a, 10a, 10a, the left 15a being trailer running lights. Drop down from there to the next 3-in-a-row set, the middle fuse being a trailer-wiring backup.

In the instrument panel fuse block at the left doorjamb, just below center and to the left are a grouping of 4-10a fuses controlling truck and trailer stop/turn signals for left and right, with the 2 lower being truck and the ones above being trailer (tilt your head to the left for proper orientation).

Check Impedance for the fuse, not just a visual. Check power to the input blade for the fuse using a small meter probe, a test light may be too large.

Below the dash and behind the parking brake is the center panel fuse block containing the 6-way trailer relay, top row, second port from the left.

Have you done the obvious and checked for damage to the trailer plug/wire harness, maybe you ran over/snagged some debris unnoticed? The stock set-up does hang low.