Motorcycle trailer lighting problem

I have a Kendon motorcycle trailer and all the lights work properly until I put the headlight switch own and hit the break. Stop lights do not work when the headlight switch is turned on. Any suggestions on what the problem might be?

LED or incandescent lights?

If incandescent:
Bad ground would be my first thing to check. Probably chafed wire or rust between ground loop and frame.

If lights are grounded to frame, I always take a Dremal tool and grind the area around the screw that attaches the ground loop to the frame. Replace the loop with new if necessary, shrink wrap the crimp area. Clean the loop with steel wool. Secure with stainless screw and then overcoat the area with liquid electrical tape.

If LED:
Individual lights usually must be grounded to frame separately. LEDs are very sensitive and must have a very good ground, almost always at each light instead of central like the old incan lights. Check all for rusted or broken grounds (white wire).

Grouse

“If incandescent:
Bad ground would be my first thing to check. Probably chafed wire or rust between ground loop and frame.”

X2. Non-linear weirdness is frequently caused by a crusty ground connection.

SR

Thanks, I’ll check it out. Everything works fine with my old lights until I replace them with two new lights. I’ll go over it again and check the grounds