Stock Drivers speaker cuts out (comes back when I crank the volume)

This is a strange issue, has anyone had the same problem? Occasionally my drivers door speaker (stock 12' tacoma, JBL/Nav unit) stops working completely. The speaker starts working again when I turn the volume up loud. Not sure where to even start troubleshooting this.

 

probably a bad connection. I am dealing with the same issue right now with my driver tweeter, everything in my stereo has been upgraded but the head unit.

I took out the head unit and checked the connections in the rear and they were good. Next step is to take off the driver door card and check the speaker connections.

 

Had this issue when I put in an Alipine power pack amplifier behind the stock stereo unit.
Basically wouldn't turn on in the mornings, but when I crank the volume it'd come on usually and stay on

It ended up being one of the wires that's supposed to 'receive' a signal to turn the power pack on wasn't connected. So the unit didn't know when to turn on, apparently..
Don't have the technical info for it - maybe that could be the issue?