[Brutus]

Razor,
my standard procedure in this situation is to check for brake/turn light power coming out of the TV and work my way back. Take a 12V tester and check for brake and turning light power at the 7-prong connector of the TV. Make sure tester has a good ground or you won't get anything coming out of the TV. You know you have a good ground when the taillight prong lights up (when you actually turn on the TV taillights of course). If nothing there, it's most likely a fuse (or two) in the TV. TV's owner's manual will show where they are. If you do have everything coming out of the TV, clean the TM and TV contacts with emery paper or steel wool. Then hook up the TM and check for brake and turn lights just behind the connection (on the TM side). Gotta take the TM's 7-prong connector sheath off to expose the wires and poke the proper wires with a tester for this part. If no brake or turn light power at that point, you've isolated the problem area. If power tests ok behind the TM's 7-prong connector, "walk it back" and test the brake/turn lights at each bulb. Normally, a burnt-out bulb or bad taillight assembly only occurs on one side though. Mostly likely it's a TV fuse or two. If not, there's a lot of info on the internet about trailer wiring troubleshooting.

Edit: Oops, just saw this is a four month old thread and Razor was a trial member. Oh well....