Radio Wiring??

I’ve done a fair share of radio work on various cars, and I’ve head plenty to troubleshoot as well.

First thing to do is make sure the radio itself is not defective. Take a little extra speaker wire (or whatever you have available) and test the output wires directly to an extra speaker.

If it doesn’t play, then your head unit is malfunctioning. Most aftermarket units will have an internal amp, and they can fail.

Once I know the head unit is good, then I will start checking each speaker individually. On the mustang, the rear speakers are the easiest to access so I would start there (in fact, one of these would also make a good test speaker if you know it works).

Once you pull the speaker, you can check the connector and wiring. If it looks good, and the wire colors match what you have up front, the. You can test the speaker. If the speaker is working, then you at that point decide if you want to trace the wires and look for a break, or just run new wire.

Rinse and repeat for the other speakers.