Trailer Lights Malfunction Help

More than likely a ground problem. Don't know what advise to give other than check your grounds. Ground problems can make you pull your hair out.

 

So they come on when you hit a bump. Is the pigtail connector loose where it plugs in to either the trailer or the cab? If you move the connector and the lights come on there's your problem. If not then it's probably a broken wire in one of the connectors, most likely the end that plugs into the trailer as that's the one that gets moved a lot.

Lots of guys pulls on the wire when disconnecting from a trailer instead of grabbing the actual plug which will cause breaks.

 

split the connectors....look at the picture above.....see how the pins have a little split in them? Take a pocket knife and stick it in that split and make them a bit wider....all of them

 

Be very carful when you do this. Too much and you will break the pins.

 

indeed.....they're brass and will break easily......just wedge them enough to split them and make better contact,,,,,mebee half way down the connector

 

I'm not trucker yet but i am an electrician. Sometimes relays build up crap on the contacts from the constant arcs overtime and also sometimes a reason of them getting hot. Hitting a bump can cause contacts not to stay open or closed. There are other relays in the fuse block that are the same most likely the AC relay you can switch it with. Obviously make sure the pins and numbers all match up before you switch them.