QuestionI took off a Pioneer navigation/stereo off a 2001 Pontiac Grand Am and have tried installing it in a 2002 Pontiac Grand Am. I purchased a wire harness from the auto parts but can't get the stereo to work. I went to Best buy to talk to a technician (purchased the stereo from them and had it installed in the 2001). The tech said I needed to purchase so module price $150 as GM required this in order for the stereo to work as GM vehicles do not like after market stereos. Is this true or is he just trying to sell me something I don't need.
AnswerHi Daniel,
A 2001 and 2002 Grand Am should use the same installation parts, so if an adapter module was used in the original vehicle, it should work just as well in the new vehicle.
In any case, here's what's going on:
The factory radio in a 2001+ Grand Am is connected to the vehicle's data bus system, and it controls some vehicle functions. In particular, the factory radio is responsible for generating all audible warning chimes--seat belt chimes, door chimes, lights left on warning, and so on. They play through the driver's door speaker.
In addition, the factory radio is controlled via the data bus system. Most cars have two power wires in the radio harness--one constant power wire, and one key-switched power wire. In your vehicle, there's just a constant power wire. Instead of a key-switched wire to turn the radio on and off, the factory radio gets its power-on and power-off commands through the data system. Obviously, an after-market radio can't communicate with the vehicle's data bus system like the factory radio can.
The expensive adapter module can communicate with the vehicle's data bus system, and it has two functions. First, it will generate the vehicle warning chimes in place of the factory radio. Second, it can receive the power on and power off commands, and use them to generate a switched power wire that can be used with the new after-market head unit.
It is possible to install a new head unit with a standard wire harness instead of the expensive adapter module. Because there's no key-switched power wire in the factory radio harness, you'd need to find a switched power source elsewhere in the vehicle. This is actually pretty easy in a Grand Am, because the key switch wiring itself can be found at one side of the radio cavity. If you use a standard harness and a separate switched power source to install the new head unit, then the original factory warning chimes will be lost.
Some retailers, as a matter of policy, will not replace the factory head unit in these vehicles without using one of the adapter modules. This is because the warning chimes can be considered a safety feature, and a retailer might possibly be held liable if they disabled a warning chime and someone was injured as a result. Of course, the high profit margin on the adapter modules doesn't hurt either.
You can almost certainly find the adapter module for a much lower price, especially if you're willing to purchase from an online retailer. In your vehicle, you'd want to look for a Metra GMRC-01 (sometimes sold as the VT-GMRC-01). You'd use the same module whether your Grand Am is equipped with the standard audio system or the upgrade Monsoon system. You can also use a GMOS-01, but this is likely to be more expensive because it's made to work with Onstar (which I don't think was an option in your Grand Am).
Hope this helps!
Brian
