68 Driver side rear light issue

[bretcopsey]

Need some direction on what to check for this problem. The driver side rear running light works as it should, but second filament doesn’t flash with turn signal or 4 way, nor will it light with brakes applied. Front park/signal works fine and passenger side all operates correctly.

I hooked up some trailer lights in place of taillights with exact same results then swapped the trailer light wiring to oposite sides and the problem followed to the passenger side so this tells me there is some sort of short upstream in the DS circuit (under dash?). Since it’s both brake and flasher I’m hoping this narrows down where I need to look. Bulbs are good and both flashers have been replaced in the fuse block. All fuses look good and I wouldn’t suspect that to be a problem since it’s just one side with an issue. Any tips would be appreciated.

[kwmech]

Could be an issue all the way into the turn signal switch. Ign on, left turn on, check the yellow wire with a test lamp at the connector at the bottom of the column

[Steeveedee]

If the rest of the lights still work, it is an open circuit, not a short circuit. A short would pop the fuse. Do like KW says, and if there is power there, follow that wire to the back until you find the break. If that wire isn't hot, it is your turn signal switch.

[bretcopsey]

Well, as embarrassing as it is, it turned out that connector was not fully seated. Pushed together until I heard a click and everything is working properly now. Thanks guys!

[Steeveedee]

Best kind of solution! Beats crawling around with a test light for an hour.