96 Isuzu Rodeo - when I switch on the right turn signal the high mount brake in the back comes on, the rear brake light left and the right turn and brake lights come on. When I depress the brake pedal the right front turn signal comes on and stays constant, the rear right turn signal comes on and stays constant along with the high mount brake light and the right rear turn signal light stays constant as well.

Puzzled, to say the least!

sounds like filament in one of your bulbs has broke on one side and is shorterd to the other. Just replace both tail lamp bulbs should be 1157

Unfortunately, it is not the filament in one of the tail lamp bulbs. I did try it, but the problem persists even with the tail light assembly disconnected.

o if you are around Lafayette Louisiana I could give you a hand with this but I would need to get into it myself all I can offer now is a good luck to you

Thanks for your help. I am in Virginia and will take the Rodeo in for surgery on Monday. I'll post what they find so if any one searches this board with a similar problem they can learn from the results.

Solved the problem:

The wiring harness for the trailer was causing the problem. Apparently, a short occurred in the plastic housing. Five wires (Red, Yellow, Brown, Green and White) attach to a connector on the Rodeo side. Then the wires lead into a small gray box and only four wires come out (White, Brown, Yellow and Green). This gray box was heating up and somehow a short occurred within. Since the box is well sealed there is no way to fix the short. However, a replacement harness has solved the problem.

Thanks for the post and you were on the right track with the idea about a short.