So I found my solution to this mind numbing pain in the ass speaker issue. I have a 2003 2500HD Bose system with aftermarket radio. Left front door speaker would not work from day one.( I bought it in 2015 ).
Aftermarket stereo came with a scoshe system that allows you to still have control at the steering wheel. Not if you have the premium stereo ( Bose system ) which is what I have.
List of things I did to correct but with no avail.
1.) change speakers
2.) swap passenger and driver speakers ( still passenger side would work which told me that my speaker in the driver door was good)
3.) checked connections at speaker found corrosion at speaker plug.
Solution was step four.
4.) run all new wire from head unit to speaker!!!!! Still not working ( really WTF!!!!???!??? )
Finally the fix or repair that worked for me.
5.) cut off old plug for speaker in door and hardwired the speaker using the original wire. Just cut down a little bit with fresh copper showing.
Hope this helps everyone cause I know you have had the same frustration as I did troubleshooting this. It's the first time I was soooo mad I could punch babies!!!! Just joking