Originally Posted by NoTLaDStyle
The chime sounds through and sometimes BCM initializes through the radio harness - its a coin toss as to whether the BCM will run without the bypass harness. Only way to tell is to unplug the radio and try to start the car. If it throws a code or your windows/wipers/etc stop working then you need the bypass harness. If they still work you can probably get the standard 20$ harness and just not have door chime.
You do need to buy the kit and it is 30$
If you have the little LCD screen it will no longer work without the oem radio.
Scosche has a kit for the cobalt and it includes the wire harness (kinda like the kit for a 97-99 Taurus/Sable, has everything in one bag). You get a little display under the radio for all your computer readouts. Unfourtunetly (sp?) its 199.99 here at BB and its a special order.
Scosche part #: GM1593B
Works with:
Chevrolet
2004-UP Malibu
2004-UP Malibu Maxx
2005-UP Cobalt
Pontiac
2005-UP G6