Left front indicator failure

[Alex_6.6]

Hey yall. I got. 2016 3500 with a Duramax. Having an odd issue that started the other night. My left blinker won’t work, when my headlights are on while I do it auto or manually the blinker indicator on my left mirror stays on (as I showed in the picture). The blinker will not work in the light but the 4 ways do. I checked all the grounds at the bottom of the radiator, under the driver door and under the passenger door. I also checked all the BCM fuses in the truck and they’re all good. Also, the first 3 blinks are normal then it goes into hyperflash. Any one have any ideas?

Edited September 20 by Alex_6.6

[newdude]

Do the bulbs in the left headlamp and left tail light flash when you activate the turn signal?  

 

Any aftermarket headlights or tail lights?  

Edited September 20 by newdude

[Alex_6.6]

40 minutes ago, newdude said:

Do the bulbs in the left headlamp and left tail light flash when you activate the turn signal?  

Yes. When the headlights are on in manual or automatic they don’t work at all when they are off they work but with hyper flash. Both front and backs the rears work at all times 

[newdude]

1 hour ago, Alex_6.6 said:

Yes. When the headlights are on in manual or automatic they don’t work at all when they are off they work but with hyper flash. Both front and backs the rears work at all times 

 

 

I'm trying to make a bit more sense of this...

 

So if you put the headlight switch in ON (turned all the way right) so all the lights are on, you have no left signals?  And this also happens with the switch in the AUTO position (which in park you should have no lights on unless its dark, or maybe just the DRLs on) it does the same thing?  

 

If you turn the switch to the left all the way to turn off auto lamps, you do or do not have flashers?  

 

How about in the park position?

 

In park and in ON, are the two orange bulbs that are the signal and markers, are they lit up with the flasher off?