I've been investigating the mysteries of my door contact switch wiring in my car. I found out the wire for the front passenger door contact switch has completely vanished and the black/blue wire coming from the driver's side of the dash goes through a sketchy bundle of tape before continuing to the rear passenger door contact switch. I'm guessing that this used to be a three-way junction and I simply need to splice in a wire going to the front passenger door.

But the real mystery is with the rear driver's side door. This one has a wire thankfully, but it does not seem to be connected with the rest of the circuit. More confiusingly, as the wire comes down the b-pillar to the floor, it goes backwards and enters the harness going towards the taillights. I thought that maybe the wire was crossing over to the passenger side to hook up with the rest of the circuit, but I don't see any point where this wire crosses over. I've tried to find a detailed diagram of the physical wiring, but haven't found anything helpful. Does anyone have any insights?