this is probably in wrong forum but i bought a 02 silv and when i checked the blinkers on the plug in for the trailer they work but the runing lights dont? do i have to buy a wiring harness to make the seven pin connector work?

 

you can use a flat 4 connector . . . what's on your trailer side, is it a flat 4 also?

 

Check the fuses under the hood, Probable just a blown fuse.

 

x2 Also if it is a fuce you want to check the connectors running the whole way from the taillights to the fuse block to make sure you didn't burn up a connector. My brake lights kept popping fuses and it ended up burning a connector and i had to wire it together when the connector wouldn't keep the current going.