2000+ factory radio replacement info
(if you have a pre-2000 J-body car.. this info doesn't apply to you)
If you have a 2000-2005 Cavalier or Sunfire, then your factory head unit/radio/cd player/stereo/whatever is referred to as a
CLASS 2 unit. Class 2 radios are wired slightly differently than regular non-Class 2 radios. Many stereo installers (Big Box stores - Best Buy, etc) are generally unfamiliar with the finer details regarding Class 2 radios, and thus there is a LOT of misinformation out there about them.
The primary difference between a Class 2 radio, and a traditional radio is the switched power wire. Class 2 radios do not use a switched power wire (also known as the accessory or ACC wire) in the factory harness. They only need a constant power wire, and the radio is turned on and off using Class 2 signals from the Body Control Module (or BCM) via the purple wire found in the harness. The BCM is what provides the "retained accessory power" so the radio stays on until you open the driver's door.
In addition to playing music, the factory radio also produces the door chimes. If you replace the factory radio from the car with an aftermarket unit.. and you do not use an aftermarket relocation T-harness or door chime module.. you will lose your factory door chimes and OnStar (if you even have it). That's it!
Contrary to seemingly popular belief, removing the factory radio from your vehicle will NOT affect:
- Airbags
- Keyless Entry
- Daytime Running Lights (DRLs)
- Cruise Control
- Oil change light (J-body cars don't even have one!)
If anyone tells you otherwise.. THEY ARE MISINFORMED!
Radio features, such as Radio Data System (RDS), MP3 player, etc are part of the radio itself and do not affect the rest of the car. The only part of the radio that has additional external hardware is the XM option, which has a receiver under the rear package shelf.
If you wish to keep your factory door chimes, retained accessory power control of the radio, and/or OnStar... you need to either relocate the factory deck using a T-harness or replace the factory deck with an aftermarket chime module for the chimes and OnStar speaker.
If you don't care about the losses of removing the factory radio.. you can buy a cheap aftermarket harness and hook up an aftermarket deck. You don't have to spend $100 or more on a T-harness to relocate the factory deck. Look for the harness for a 2000 Geo Tracker or Chevy Trailblazer. Using a harness is a much better solution than cutting wires. DO NOT CUT THE WIRES because it's just more work for you trying to figure out which one is which (and yes, there are sometimes more than one of the same color!)
When installing an aftermarket deck, you'll need a deck mounting kit and a GM antenna adapter. You also need to find a switched +12 volt source to turn the radio on and off, as the Class 2-equipped cars won't have this wire in the factory harness. The easiest way to do this is to buy an "Add-a-Circuit" plug at the automotive store (the small fuse one, not the regular size) and plug it into the windshield wiper fuse on the side of the instrument panel. The windshield wiper fuse has power when the car is ON and in accessory (ACC) just like the factory radio. Alternatively, you may wire the switched power to the constant power, and the radio will stay on at all times.
More information on the Class 2 radios found in J-body cars can be found here:
http://members.shaw.ca/johnz24/howto/
And in the JBO forums:
http://www.j-body.org/forums/read.php?f=4&i=51826&t=51826
http://www.j-body.org/forums/read.php?f=4&i=118462&t=118462
