Hi, so I recently purchased a 2006 Acura TL from a private seller and I've found some pressing issues with the electrical side of things, that I think may lead back to the aftermarket radio that was installed by one of the previous owners. For reference it's an old double din touchscreen radio that doesn't have car play. Not sure of the exact model of it either as there's no printed logo on the housing. Anyways, I'm imagining whoever installed this thing did a crapjob with the wiring somehow because i think it's causing issues in other parts of the car.

For instance, my navigation screen no longer seems to function properly. When starting the car, it will flash the boot screen and go to the passcode option but I'm not able to interact with it whatsoever, (touch/buttons) and then it promptly shuts off after around 30 seconds. It doesn't flash any of the normal error codes for nav issues like some other people experience.

I'm also having issues with the buttons below and on the passenger side the nav screen either not working at all, or working, but with no backlight.

On top of that, my horn doesn't work, and my steering wheel buttons do not work either for adjusting volume or for interacting with the navigation screen (which again, does not work)

And finally, or at least what I can think of off the top of my head, there's a constant whine/ droning from the aftermarket system that gets louder whenever I accelerate or turn.

I'm newer to working on cars so I haven't gotten around to testing the fuses yet, but any guidance on how to assuage this situation or point a new TL owner in the right direction would be much appreciated 🙏