Radio wiring cleanup for the MX-5


Friday, July 31, 2026.

Something's been rattling around behind this cheap aftermarket radio for a while. I've been putting off dealing with that because it's annoying to pull the radio and lose all the settings on it, but I decided yesterday was the day.

Oddly enough, it seems like every car radio does that? I figured it was just because this one's cheap that they didn't want to spring for settings NVRAM, but I looked at some much higher-end DIN radios and the manuals say that they lose settings on battery disconnect as well. They've all got USB ports too now and none of them support backing up settings to a flash drive. Why the hell do we put up with this shit?

You can tell this was installed by a professional. This stereo install was just about the first thing I did on the car, since I bought it two weeks before going on a 600-mile road trip and the factory stereo was busted. I suspect those little plastic wire nuts are making noise by bumping into things, and the bracket for the radio itself isn't that secure in the console faceplate thing.

So the first order of business was to cut all the important wires a lot shorter and connect them with crimp terminals. This is just a little adapter harness that goes between the car's actual radio connector and my aftermarket head unit, so there's no reason to be delicate with it. These are heat-shrinkable crimp terminals, but I didn't bother shrinking them because I don't have a good heat gun and it's a connection between two non-watertight connectors that shouldn't be under any strain.

With that done, I took a bunch of wires I don't need out of the connectors. Both sides of the harness are wired for two rear speakers, a control line for a remote amplifier, and a control line for a power antenna, none of which are things this car has. I hadn't bothered to connect those wires, they were just sitting there, so they're gone now. I'll probably install rear speakers and a dedicated amp in the car in the future, but I'd be redoing all the wiring for that anyways.

I did bother to actually remove the pins from the connectors instead of just cutting them, except for one wire on the steering wheel controls plug that didn't want to come out at all and I decided I was only gonna spend so long trying. (That wire isn't for anything this car can possibly do anyways, so there's zero chance I'll want it back later, which technically isn't true for the others.)

And it still works. Except it's blue now, because one of the settings that gets lost when you reset it is what color it's supposed to be. I also determined that the factory iPod interface box sitting behind the HVAC controls could be removed easily, so that's gone too (barely visible in the passenger footwell).

Anyways, now the car rattles a lot less. There's still a bit of noise coming from the dash somewhere, and the passenger side door is noisy because it's missing a bunch of clips for the door card and the outside door handle is loose (which I am not looking forward to dealing with).

Coming up next on the car is paint repair. I've ordered some stuff for that, so keep an eye out here in the coming weeks to see how it goes.


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