If you are pulling the radio to check the wires, I suggest you might be prepared to redo all the speaker connections. When I pulled mine, the connections were poorly installed wire nuts. I removed them and replaced them with soldered /heat shrink sealed connections.
2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 100W solar panels