Nad_Yvalhosert
I'm Awesome
On my 98 auto 4x4 the switch under the dash with the green wire is NOT for the backup lights. Instead, the neutral safety switch/backup light switch is on the drivers side of the transmission, near the driveshaft. In any case for me the problem was in the tee connection to the trailer wiring. It was loose and would not tighten, so I clamped it together with a zip tie.
Hey, it's great to be helpful, but O.P. was working on this problem 12 years ago. I assume it's been fixed for over a decade, because he hasn't been seen here for 9 years...