I recently posted a question regarding a speaker problem on the driver's door. I've since determined that it is not the speaker nor the head unit. It is definitely the wiring. My question here is about the harness that attaches to the door jam. Is this a plug that goes from the door to the frame? It appears to be a plug in the event you had to remove the door. Can someone clarify if this true. My thinking is that I've possibly got a loose connection at that junction. I'm trying to isolate where my problem is. Any help or clarification would be helpful.

Thanks ahead!