Front turn signal wiring help

[87Skier]

I'm having trouble getting everything working in my 72 GMC Jimmy. I am redoing my harness and adding a fuse box under the hood so the headlights are switched, and a few other components.

To do this, I used the original harness as template and copied it exactly. I noticed that when redoing my harness that the front turn signal and front marker lights are wired together.

When the lights are off, the front marker and turn signal both flash.

When the lights are on, the front marker and turn signal do not light up. When I turn on the turn signal the lights come on solid and do not flash.

Can anyone shed some light on this?

Thanks