Something as simple as a tail light

[tivoliman]

The 1990 300E 2.6 has a wiring problem

The tail light on the right side does not work. And the 'Light bulb fault light' is on on the dashboard.

• Replaced the bulb - still doesn't work
• Fuses all good, but rotated all - still didn't work
• Brushed the socket clean - still doesn't work
• Took the light panel from the right side, and plugged it in the left side - The light worked.
• Traded Light Control Module with another car (gold) - same part number - No change. The light status (tail light and dashboard light) remained the same with the Light module switched between cars. The Gold car lights worked fine with the module from the black car.
• I hunted down the wire, and confirmed with a wire diagram - the wire from the light module to the light bulb socket is GR/RD (gray with red line). I tested resistance on the line - it showed 3 ohms, which seemed like a lot. But it showed connectivity - so I figured the worse would be a dull, but functional light.

I need a creative approach.

What else should I test.

Would the Gray/Red wire at the tail light be the same Gray/Red in the fuse box area? Or could there be more than one wire that's gray with red stripe?

Thanks for the help.

It will not pass state inspection while the tail light is out.

Another hint:
The dash board light comes on when I press the brake peddle, but all teh brake lights are working.


Why would the right tail light not light, and the