Left turn signal weirdness

[WascallyWabbit]

Hey. Need some group think from y'all.
I have a 2003 TJ. The other night the left blinker stayed on. When I checked. It worked in the rear and the left fender, but not the forward facing signal. Right side is totally fine and hazards work on all 6 just fine.
To make it even weirder, it's only when the headlights are on. When they are off everything seems to be working fine.
I replaced the relay which doesn't seem to be the problem. And it's definitely not the bulb. Before I go chasing wires, I thought I'd hit up the form and see if anybody has any thoughts whatsoever

 

[Rubiconned]

MFS?

 

[WascallyWabbit]

Thank you. Took a look there and could not see any loose connections or wires there and before completely disassembling the MFS, I wanted to check a few other things. It appears to be a loose fuse in the number 13 slot behind the glove compartment. The fuse was still good but may have been sitting just slightly ajar. Reinserted it and it seems to have fixed the problem... For now.

 

[RangerTJ]

I had this exact same issue and ended up replacing the switch.

Mine would work fine for a while, then decide to hang, and then work fine again.

No issues since switch replacement.

 

[LONGJP2]

Most likely the switch

only when the headlights are on.

but this could make it a grounding issue too.