1987 Nissan Pathfinder 87 Pathfinder driver side low beam f

Hello,

I have a 1987 Nissan Pathfinder, and the low beam on the driver headlight is not working. High beam is ok. Both filaments on the bulb are ok, and if I check the voltage at the connector with the bulb removed, I get 12V for both the high and low beams when selected. However, when the bulb is actually in place, the voltage for the low beam drops to near zero when low beam is selected. If I jumper the low beam wire to the hot battery terminal, the low beam filament lights up. Same ground is used for both filaments, and I have further verified it is not the ground.

So, I seem to have isolated the problem to the low beam hot, but not sure where to look from here. Is there a relay somewhere I should check, or how should I proceed with the troubleshooting from here?

Thanks for any advice,

John