Car Stereos: wiring harness, seatbelt reminder, gm cars

Question
do i need a special wiring harness for an 04 grand am

Answer
Hi Craig,

In a 2004 Grand Am (as well as many other newer GM cars) the factory radio is interconnected with the vehicle's data bus system, and the radio itself controls some minor vehicle functions.  Most noticeably, the factory radio generates all the vehicle's audible warning chimes (key chime, lights left on, seatbelt reminder, etc).  If you remove the stock radio, you'll lose all audible warning chimes unless you use a special adapter module.

Additionally, after-market head units need a key-switched accessory power wire to work properly.  There's no such wire in the Grand Am's radio plug, because the factory radio is controlled directly by the data bus system.

If you're installing an after-market head unit in this vehicle, and you want to keep the warning chimes working, you'll need the adapter module. A popular adapter is Metra's GMOS-01 or GMRC-01.  Either will work in the Grand Am, but if your car is equipped with Onstar and you want to keep it working, you'll need the GMOS-01.  If you don't have Onstar, you can use either module.  These modules include a switched power output that can be connected to the after-market head unit's accessory power wire.

If you don't care about keeping the warning chimes or Onstar, you can install a new head unit without using an adapter module.  In this case you'll want Metra's 70-2003 wire harness.  You'll need to find a key-switched power source somewhere else in the vehicle for the accessory power connection.

In addition to the adapter module or wire harness, you'll need a mounting kit (part number 99-2003) and antenna adapter (40-GM10).

Hope this helps!

Brian