Bad tail light wiring

Hi All - I have a problem with the left tail light on my new to me 2002 Jayco Qwest.  The tail light itself works, but the turn signal, brake, and flasher do not.  Everything works correctly on the right side.  I assumed the problem was a bad bulb, but it turns out I’m only getting about 2 volts to the wire that powers the turn break and flashers.  I’ve reached in and pulled out that wire as far as I can and from what I can see there are no bad connectors there.  Anyone have any thoughts as to how I can get a new wire routed to that light.  I don’t see any access inside or from the bottom.  Just FYI , the wire scheme is as follows:

Right light (works)
Tail light - Green
Turn, brake, Flash - Brown

Left light (only tail light works)
Tail light - Green
Turn, brake, Flash - Red (only 2 volts).

Thanks, Any help appreciated.