When I got my 05 grand prix, it did not have a radio in it at all. I bought an aftermarket radio and took it to best buy. They installed the radio, and then afterwards told me that the insturment gauges would not work because the computer in the car was searching for the factory radio. I don't understand why the gauges worked without a radio in it at all, but then they put one in for me and all the sudden none of my gauges work properly. You can just be driving down the road and all of the sudden the speedometer, rpms, temperature, and gas all go to zero and won't go back until you restart the car. They said if I buy a factory radio they can wire the radio to the trunk and this will fix the problem.
My questions:
1. Is this true?
2. If it is true, can I buy a factory radio that doesn't work or does it have to be a working factory radio?