Tail light problem :(

[brenno0]

Hi guys, I own a 2001 cougar, I'm having a problem with the rear tail lights not coming on when I turn on the side/rear setting. All other lights on the rear work (brake, reverse, rear fog). It just wont seem to turn on the tail lights for night driving....if anyone could help it would be appreciated.

[Evgeni]

It would most likely be a high ground on your tail light circuit. When the lights are off, the light is drawing from a shared ground in the circuit. Turn the lights on and there is no ground available probably due to a partial short to power.
You need to test the power/ground at the bulb socket.
Solutions for should it be a faulty ground would simply be grafting a new body ground to the bulb socket or to replace the tail light wiring loom from a wrecker, provided the bulb socket is all ok.

[REDDYZ]

Another way of checking the circuit is to turn on the parkers. I'm not talking about normal parkers that will turn on while driving. Turn the headlight switch to the left with engine off (may be with key out as well) this will turn on front and rear parkers without dashboard lights. I can't remember what this setting is called. Anyway try this and see if it turn on the lights. It could also be the switch.