blinker light on with headlights,

[LQQKING4U]

left blinker light in dash comes on with headlights, new build using painless wiring, headlights, taillights, brakelights, parklights, blinkers, all work engine runs gages work, ground wire by fuse panell tight tried a extra ground to dash
Thanks for any help

 

[serial car restorer]

Does it flash properly with the left turn signal if the headlights are off? And does it matter whether the headlights are on high or low beams?

 

[66broncoCT]

Check/clean/replace your headlight ground. Every time I’ve had this happen in various vehicles it’s always a bad ground at the core support

 

[73azbronco]

Grounds are off.

 

[DirtDonk]

Are the front turn signal buckets new? If so, one or both are probably wired backwards.
If this is the case, when you turn the running lights on the bright filament comes on, and illuminate the turn signal lamp in the dash.
Does it come on as soon as you pull the headlamp switch to the first position? Perhaps start by disconnecting the turn signal lamp up front to see if it changes.

 

[bronco italiano]

Interesting DD. My buddy's half cab is having the same issue.
New painless harness
WH LED headlights
Left turn signal light comes on when parking and Headlights lights are turned on.
I took off the front turn signal assembly, as it was not in the best of functional shape, and the left turn signal light did not come on so we are replacing that assembly and will see.