Speaker Wiring on 86 C10

[SkidRo]

I have an aftermarket stereo in the truck. The original speakers are in the dash and there are two 6x9" (not sure of the exact size) in each lower corner behind the seats.  They are in enclosures which may be original as far as I can tell. The passenger front speaker works all the time.  The passenger rear works when I hit a bump (something is loose).  The driver side speakers do not work at all. I removed the rear speakers and traced the wires all the way up to the front speakers (passenger side) and they look fine.  On the driver side speakers it looks like one wire goes to the fuse box, which is confusing me, while the other travels up deep underneath the dash.  I am decent at wiring, especially stereos and speakers, but I cannot figure out how the speakers are wired.

Does anyone have a quick reference guide on the factory wiring and can explain why the driver side has one wire from the rear going to the fuse box?  Maybe the passenger side does too but I haven't been able to find any indication that it does.

Thanks,
Rory

[zieg85]

The speaker looms do not go to the fuse box but goes around it.  I've removed the speaker looms on stereo equipped trucks before.  I actually need to get one now as I gave my last set away

[SkidRo]

Thanks, that makes perfect sense. I will look at it again. It really appears though that one lead from the rear speaker is plugged into a slot on the fuse box. 

I will end up removing the after market stereo and running all new wire once I see what I am dealing with.