Audio Systems: speedometer stuck at 10 mph, radio wiring harness, chevy cavalier

Question
i just had a after market radio installed in my gf's 2005 chevy cavalier and the speedometer is stuck at 10-20 mph what is wrong?

Answer
Don't want to scare you but this is bad, you are going to have some serious problems in the future, you lost all your warnings air bag is not going to work, lights on key on the ignition low fuel no fuel and gauge is not going to work and in a couple of week you will see the THEFT green light and the car is not going to move anymore, solution is going to be your car tow to the dealer and they are not going to fix it unless you put the oem radio back,

all this because the person that did the installation, don't know what they are doing

you need to replace the radio wiring harness, at the moment the body control module is not getting one of the data information from the radio

http://www.oemautosound.com/pc-218-132-pac-c2r-gm24.aspx