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So, if any three speakers (excluding the sub) are connected the three work; but, if you hook up the fourth, none work? Recheck all your wiring and connections.
The left front wasn't working / shut off the volume when connected. I disconnected the LF speaker wire at the radio and used the wires from the LR radio to the LF speaker and it worked, so not the speaker. I connected the RF speaker with the other set of radio wires and off it went.