Marker and Tail lights stuck on

If anyone is an electrical guru please help. When I turn off the truck and have the headlight switch in the off position the front marker lights, the tail lights, and the interior cluster illumination lights say on. Only way to get them to turn off is to pull the "tail" fuse or smack on the "tail" relay in the fuse box. I have already tried replacing the relay and still same symptoms. I Have also checked all the bulbs and also pulled the trailer harness off the truck. Any other ideas would be much appreciated.

 

Well if smacking the relay shuts them off but a new relay did not fix the issue your getting voltage from another circuit in the fuse block area .

Any new electrical parts added?

Parts of a left over alarm can cause this .

Any electrical devices that are not working??

Have you checked that the switch is working like it should with your meter ??

Switches do fail in this fashion more often they no longer work at all.