I bought my 2003 G35 sedan from someone who had put in an aftermarket (Alpine CDA-9856) system. Personally, I like the factory unit better, so I just bought one and tried to install it today, but after all was said and done, it didn't work. I think its because they changed the wiring for the aftermarket unit, and now it's all messed up.
Does anyone know what I need to do? Does anyone have pics of something like this? How much would it cost to ask a dealer just to wire it back up? I can put it all back together, just confused about the wiring situation.

 

Check to see if your car still has the Bose Amp associated with the upper level sound system (thats if your car came with the factory Bose). If the previous owner did a complete audio retrofit and you will have a hard time getting the factory bose head unit to work.

 

You have to get the right OEM radio. If your car has the Bose system, you need a Bose radio and likewise if your car has the non-Bose radio, you need a non-Bose radio. Look on the back deck under the rear window to see if you have a grille with the Bose label on it.

Honestly, you should have kept the alpine in there. The factory radios are not very reliable.

 

Surprisingly, I got it to work perfectly!...all is well. The only thing that I didn't get to work are the steering wheel controls. They didn't work when I had the alpine in there either, but I noticed that there was an adapter behind there that should have made it work with the alpine....I dunno

 

THere should be a wire harness bundle behind the HVAC unit that plugs into the stock HU that enables the steering wheel controls. You wouldn't utilize that harness with an aftermarket HU so it would be lying around back there tucked away maybe....

My only question would be why you would go back to the stock HU where you'll inevitably get the F3 CD errror for the CD changer and the passenger side speaker will cut out....all the problems people who have the stock setup experience and want to get away from.

If you had an aftermarket HU, you had the Titanium DD Dash Trim which is a hot commodity these days, you might want to sell if if you aren't going to use it.

hope this helps....
doc