It figures that my tail light/signal light is out now that I am planning on getting rid of it. And by "get rid of it" I mean scrap yard

The signal went out. I replaced the bulb and all was well for a couple of weeks. Then it stopped working for a bit. Then it worked for a day and then it was just when ever it felt like it! And now its down for the count!

So the signal/brake light is not working (driver side). 3 wires and not one of them is powered when I have the left signal on. I was hoping it was something easy to figure out and fix. Like a bad ground.
I'm wondering if the black is in fact a ground. If I take the bulb out I should be able to test to ground each wire with an ohm meter. I did test each wire to each other for power and got nothing.

I tried finding a wire diagram without much luck. Found ones that are similar but the wire colours don't match up.

Any ideas out there?
Thanks

 

Check my signature below. So it's 4.6L or 5.4L?

Additionally you said you replaced the bulb so the old bulb blown or not, you tried it on the passenger side?

 

Hi Heiko. It's a 2010 E - 150, 4.9l, 2WD, Auto, Half to find the vin. Ya I replaced the bulb and it worked for a few weeks and then all this trouble. But wait thats not all. The driver side low beam went out tonight! What the hell.