tailights not workin

[Slik69]

Anyone have issues with rear lights. Everything is hooked up (to my knowledge) but the rear light are sometimey.. meanint they work when the want to. I looked underneath truck and do not see any wires shorting out or not connected. Sometime when I go over bumps (hard bumps) the light will pop on. They have only worked once since I had the truck. There are a lot of loose wires inside as well under the dash.

Does anyone have a wiring diagram or know where I can fine one on-line.

Thanks