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Tail Light Issue!!!

843 Views 3 Replies 3 Participants Last post by  delta3835
So I have a 2007 Mustang Gt Convertible and I'm having an issue with my tail lights. When braking or signaling, the left innermost light does not work, but if the headlights are on all of the rear running lights work just fine. Is this a wiring issue? Obviously the bulb is fine so I don't even know where to begin with diagnosing the problem.
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I have a feeling it is actually the bulb unless you have tested/replaced it and it still does not work.

Swap that bulb out with a different one (like the outer most bulb) and see if the issue follows the bulb.

Running lights use one element of the 2 filament bulb the brake/turn signal/emergency lights use the second (brighter element).
If your taillights are stock ie "No sequencer" the inner most tail light lens does not have a brake or turn signal function. 'Tis true the bulb is a dual element but look at the socket. Only two wires, not three. I don't know why Ford did this. If I had to guess, it was a smart junction box power problem.
Interesting! I had no idea that the tail lights were dual filament. Here I was thinking it was just one and that it could't possibly be that simple. :laugh2:
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