The trunk light in my 84 300SD does not light up. Tested with a jumper from a known good 12V Dc source and the light works. There 3 wires, 1 red/yellow, 1 Blue, and 1 Brown. I removed the rear seat back and found that the wire bundle goes up into the headliner, where does it go from there? Any help is appreciated as always. Thank you.

The favorite place where the wire breaks on this setup is right where the wire crosses the boundary of the lid into the trunk. The wires constantly are moving at this location and it's not too difficult for one of them to seperate after 23 years.