Ground Issue - Tail Lights Blinker

[TA_C10]

I have an issue right now where I turn on right turn signal, and right tail light blinker works fine, but the left tail light blinker and left bedside marker light also blinks with it(dull but it blinks). Pretty sure it's a ground issue.

When I hit the left turn signal, it works fine, and right blinker and beside marker don't blink with it.

Only when I hit the right turn signal is my issue. All lights are LED. I do not have my front park/turn/bedside marker lights hooked up yet, this is a new installation.

I checked all the grounds at rear of vehicle, they are all grounded well. If I have a problem in the cab harness, which ground in the wire harness would it be? I don't see a ground connection specified in my new American Autowire harness specifically for the turn signal switch. Does it even have a ground connection for the switch at the column?

I have a new LED blinker relay installed in the fuse panel that has it's own separate ground wire that is connected to a ground buss on my firewall. I checked this and it's good.

Thoughts?