Trailer light failure

[madtownrover]

My trailer's running (tail) lights failed on a recent trip home. I tested the LR3 4 pin and it appears there is no voltage to the running light. The trailer brake and turn signals work fine and test fine at the LR3 harness. As far as I can tell, there is no fuse controlling the trailer running lights.

So, the failure appears to be at the LR3, probably the wiring harness. Is there a "controller" that may be malfunctioning? Separate from the wiring harness?

 

[madtownrover]

update on trailer light failure

I tested the 7 pin connector on the LR3 harness and it does have running light voltage. The 4 pin connector does not, so I'm guessing there is a bad wire/corroded connection in the end of the LR3 wiring harness. I'm going to pull it and check the wires behind the plugs.

 

[huelsmma]

There is a 10amp fuse for running lights. I blew mine last weekend when i was rewirin my trailer. That was after i realized that my boat trailer needed to be on my ball mount to get the proper ground. I was puzzled bc everything was showing good from the lr3 plug but when i connected the trailer lights without it sitting on my ball, i had different results.