I have a 2001 quad diesel, my back up lights wont turn off even with the key out of the ignition.

 

Sounds like a short in the trailer wiring harness/plug.

If you still have the factory 7 pin plug on the receiver hitch, check in the end and make sure you don't have anything in there that might be causing a connection. But the more likely culprit is worn through wires in the harness feeding the plug that are allowing voltage from the +12V circuit to feed into the backup light circuit.

 

I had a similar problem with my trailer wiring. My passenger side brake light was stuck on and it was caused by a short in the trailer wiring.