tail light wiring

[2kayakers]

A turn signal light on my popup doesn't work, but only when the bulb is inserted.  I've checked the voltage and the socket seems to be getting power (in that the volt meter registers an increase in voltage in sync with the other turn signal bulb).  All seems to be well except when the bulb is inserted.  I've substituted working bulbs more than once to ensure that it's not a bulb problem.  I've checked the socket itself to see if the contacts are seating, and they seem to be.  Tail lights work fine.  Opposite side turn signal works fine.

If I had more hair, I'd tear some out....

Suggestions for further tests are welcome!

Thanks.

[Ghostman]

Man you are stumping me too. the only thing i can think of is the ground on the socket. Are you testing probe on the side of the bulb socket for ground or some where else. Check your resistance from the bulb ground to the chassis and see if it is correct. It would have to be ground if you are showing voltage.  If you hold one probe on side of socket and the other to the center and still show voltage I have no idea then.

[2kayakers]

Thanks for the suggestion.  I use the side of the socket as ground source.   The ground is common for both the tail light contact and the turn signal contact.  Since the ground works for the tail light, I assume it's good for the turn signal filament as well (dual filament bulb).  Also, when I put the bulb in backwards (with a little fiddling), so that the lail light contact touches the socket's turn signal contact, then the turn signal filament lights up.  I think I must be missing something basic.  I'll try your suggestion about checking resistance ground to chassis and see if that produces any enlightenment (no pun intended).  Thanks much.

[Ghostman]

Figure it out yet? I was just curious.