OK, I'm having this same problem. My new LED turn signals do not work. Larry (I think that's his name) at Classic LEDs has been more than helpful and he's the one that put me onto the fact that the car has two separate flashers and that I must have replaced the emergency flasher. I cannot find the 2nd and presumably the turn signal flasher. There are two, correct?
Son of a ! You guys weren't kidding! Good thing I already had the lower half of the dash already out. Even then I still have to remove 3 major pieces to get to it. Thanks guys for giving me the faith to continue looking!
The easiest way to find it is to fallow the click. So everybody should find it now wile it works instead of searching blind when it doesn't.
If anyone is interested in these LED rear lights, here's where I got mine: Larry was more than helpful in troubleshooting to get this to work. I'll post pics later wasn't I get the tail put back together. Larry Bush, Owner ClassicLEDs NorthWestMustang 541.463.7623