trailer hitch wiring problem

[greybeards22]

My round plug on truck has power coming out of it on all terminals, my round to flat adapter has good contact between in and out terminals.. Problem;With adapter in place(round to flat) I have no running lights power (with the lights on )to the four pin end of adapter there is power to turn signals .. What up??

[Tundraman10]

I think you should first try to electrical spray. You can get that at any auto parts store. spray the plug on both the flat and round converter. Try that first. If that doesn't work, try replacing the round to flat converter.

[greybeards22]

The problem was a bad fuse...