I have an '09 F-350 and the left side turn signal wont work in the headlight assembly or in the mirror. The rear turnsignal in the breaklight assembly works. Before I get the obvious....Yes I have replaced the bulbs.
The front signal also serves as a running light and works correctly when the lights are on. When I turn the left turn signal on, the sound of the signal in the truck is fast like a bulb is out or circuit isn't complete. I have also checked the turn signal fuse in the panel and it is fine, even swapped out fuses. Made no difference.

Has anyone had this happen to them? If so did you fix it and how?

Any help would be appreciated.


Thanks.

 

I don't have 2009 wiring diagrams, but I do have the 2008 MY diagrams which I suspect will be the same. My comments are based on the 2008 diagrams.

You're correct. An open circuit has the same effect on a thermal flasher as does a burned out bulb.

The flasher unit feeds into the multifunction switch (MFS). For the turn signal function, it is split inside the MFS into two outputs; one for the rear of the truck (corners & trailer) and one for the front of the truck (front corners, mirrors, & cluster indicators).

The rear signal comes out of the MFS on an light green/orange wire while the front signal comes out on a light green/white wire. Pull the column covers, perform a visual inspection, then check these wires with a test lamp or meter. If you don't have the correct signals coming out of the switch for the front, then the switch is bad.

 

I will check that out. Thanks for the help. I will let you know if that is the problem. Thanks.