All of my lights were fine a few days ago. I replaced the license plate wiring/socket and now neither of my tag lights and neither of my tail lights work any more. Everything seems to be attached tightly and nothing seems overly corroded. My brake, reverse, and turn signals are all fine. My rear side marker lights are also out.

Any ideas?

 

Did you reverse the positive and negative wires going to the socket you just installed? This will put a ground on the circuit blow the fuse.

 

It's just a plug in piece. Would be impossible I think to reverse them. Which fuse handles those lights? The Acc? It's a '79 F-150 BTW.

 

Check for voltage to the connector on the driver's side under the bed near the rear bumper. Also check resistance across the contacts by plugging into the wire side of the connector. Tail lights are the solid brown wire. If that is no go, check at the connector under the hood on the driver's side under the hood next to the firewall. These get corroded sometimes and will drive you crazy. I chased mine for two days. The contacts on the underhood connector were corroded so slightly you couldn't see it. If I unplugged them I had voltage, plugged in and nothing. Resistance from corrosion was so high that the load from the lights dropped the voltage to nothing. Cleaned them and got nice bright lights. When you put them back together use some dielectric grease to keep moisture out of the connectors.