tail lights

[stepper459]

1972 f100 custom: My parking lights work, but when I step on the brake or flick the left blinker, the left rear light goes out completely. The license plate light appears to be wired to the side marker light (not factory, I presume) and I just changed the license plate light. But why would that make the tail light go OUT when I step on the brake. For the record, the Right lights function normally. Any ideas?

[stepper459]

important: I forgot to mention that this is all with the parking lights on. Also, the left light goes out when the right blinker is activated. BUT with the parking lights OFF, the left blinker turns on but doesn't blink.
<p> it's gotta be something simple but what is it?

[ezernut9mm]

sounds like your turn signal switch in the column is bad. i had a 66 that would do the same thing and i replaced the ts switch and everything worked fine.

[stepper459]

duh.. I went outside to put the thing back together for the night and what do you know, the tail light unit needed to be grounded to the body to work. All better... haha

[stepper459]

thank you for the quick repsonse though!