phixnguyen

Hey I have a 2018 Audi a4 ultra premium plus with a B&O sound system I wanna replace the factory sub and add on Amp (I have the kicker key 500.01 ) and maybe add a another enclosed sub also how do I wire that also I cut the factory harness already so I can’t go the plug and play route

Hunter2017

Have a local shop fix the wiring and skip the sub. You'll end up wasting a stupid amount of money. This isn't the car to be messing around with wiring without knowing exactly how the system works. Never cut a wire in a car without a solid plan.

142 guy

Messing with the wiring harness on an A4 without the wiring diagram information in the service manual is just an invitation to poke yourself in the eye with a sharp stick and end up with a completely dead Audi A4. Go to erwin.audi.com, set up an account, pay for 1 day of access and download all the service manuals for your VIN. Start with the wiring diagrams in the electrical section to try and figure out what is going on and what you need to do - have fun with that.

You don't do anything on a modern Audi without the service manual.