Need help with lights

Here’s my situation:

’97 518 Ranger Comanche / ’96 Dodge Ram Truck

Never really noticed this before, but when my parking lights are on and I hit my brakes, the rear trailer lights go completely off.(truck lights work fine)

With the parking lights OFF, everything works just as it should.(both truck and trailer)

All other lights/signals are working properly.

I’ve done a lot of troubleshooting already, but please give me your thoughts as to what might be causing this, and i’ll let you know if i’ve tried or tested it.

Thanks fellas.

I had this on my last trailer. I can’t remember if the ground was loose or if the ground wire had a bare spot touching metal. I had both problems, but can’t remember which one made the lights shut off.

Yes!! Make sure you have a good ground. All trouble I have had is mainly from the ground.

Slop,

Jeremiah,
I had that two years ago with my chevy. It was a ground.
We can put people in space, you would think that we could wire a trailer better.

Ron

I agree and believe it’s the ground to your parking lights…If I’m wrong, it’s the ground to your brake lights.

As much as boats and cars have improved over the last ten years, a person would think that trailers and lights for trailers would have improved a bit too.

Had the same problem last year. Since the trailer was being grounded through the hitch, the ground wasn’t complete at times (stepping on the brakes, lights go out…what?). Sprayed some WD-40 on the ball and up into the latch, started working and after turning enough corners I didn’t need to spray the WD-40 on anymore.

To initially trouble shoot the problem I took a length of wire and connected it to the truck’s ground wire. Then when connecting the ground wire to a bare metal spot on the trailer, the lights were no longer possessed.

Mr. Shaver, Like the rest of the responses stated, most likely a grounding problem.
Most likely a rusted ball and receiver. You wouldn’t believe the crude that accumulates on the underside of the receiver. One way to make sure you always have a good ground is to get about a 3 1/2ft length of battery cable and 2 of the best alligator clamps you can find. Attach the clamps to each end of the cable and attach same to the truck frame and trailor. You’ll always be well grounded, even will rusty balls.
Compliments from Lake Doofuss

Same thing happens to me, but only with my passenger side rear light.