563 bulb question

[BGJ]

I have a 85 coupe. I was replacing interior lights. The passenger side floor lamp requires a 563 bulb. I just bought two new ones. I have power to the circuit (tested with 12v test light). When I install a new bulb, there is no light from the bulb, but when I check the circuit, there is power on both sides. In other words, the filament is not broken...power flows through it.

I have checked the bulbs with an ohm meter...shows no resistance.

I have cleaned the contacts on the bulbs and socket. The bulbs still do not light up.

My battery shows proper voltage, but still no light. The glass on the bulbs appear intact. Why would they not light up? I've never seen this happen before. What gives?

 

[KOPBET]

... but when I check the circuit, there is power on both sides. In other words, the filament is not broken...power flows through it.

This is exactly why it doesn't light. One side of the lamp should be at battery voltage and the other at ground with the circuit energized.

Is this the only lamp affected? If so, then it seems logical that the path to ground has been broken.

 

[BGJ]

Yes, I just found the problem.

This is the only light affected.

The path to ground on this wire has been broken. I followed the wire. It leads up into a large group of wires (probably 3/4 to 1 inch in diameter). I assume it leads into the wiring harness. I didn't want to cut into the large group of wires to follow how far this wire goes.

Does anybody think I could safely ground out this ground wire for this light to a good ground?

Would I need to put a fuse on the line?