Here is a post from another forum that explains what is controlled and what is not:
Class 2 Data Vehicle ConcernsMetra's 70-2003t and 70-2003
Applications:CHEVROLET - 2000-01 Cavalier, Impala, Monte Carlo, and Venture. 2001 Malibu GMC – 2002 EnvoyPONTIAC – 2000-01 Sunfire and Montana. 2001 Aztec and Grand AmOLDSMOBILE – 2000 Silhouette and 2002 Bravada Note: The 2001 Venture/ Montana/Silhouette do not require the SP-2003 chime module.
Metra’s 70-2003t is a 15 foot “t-harness” that will allow the installation of an aftermarket radio while keeping the factory radio (somewhere accessible) in the vehicle to retain “vehicle customization”. This is required because the radio is used as a control panel to communicate with the vehicles computer for the customization of certain “convenience features”. All features work and remain at current settings with the factory radio removed, but can only be customized and/or reset by an authorized service center. In my belief, the door chime is the greatest loss, which is inoperative without using the 70-2003t in conjunction with Metra’s SP-2003 chime module (self enclosed speaker) mounted under the dash. This will keep the chime to its factory settings. Metra’s 70-2003 can be used instead, but the factory door chime will not work. There is also no switched 12vlt. power supplied in the radios plug, so it will need to be sourced somewhere else such as the factory fuse panel. A 15 to 30 amp fused accessory power source is recommended. Depending on the vehicle there are several choices in the factory fuse panel, such as the sunroof or windshield wipers. Both the 70-2003 and 70-2003t include a 42” red wire with a fuse tap at one end. Vehicle Customization Menu Options: (Most Cavaliers, Sunfires and other base models do not offer most, if any of these features. Check the vehicle owner’s manual to see available features.)
Displays current settingsOil life monitor resetTire inflation monitor resetDelayed headlamp illuminationAutomatic door lock and unlockRemote visual/audible verification of remote lock/unlockEnable/Disable content theftEnable/Disable trunk lock shock sensorShort or long horn with remote lock/unlockKey fob transmitter programming
For the Cavalier air bag concerns:GM’s service document numbers 537803, 558212, and 558208 give detailed instructions on removal of the radio. Document 537803 is the basic removal and installation referring to 558212 for the trim plate bezel replacement, and to 558208 for disabling the SIR system. Not suggesting things shouldn’t be done to procedure, but I‘ve spoken with a handful of GM service techs and not one follow these procedures when removing a radio. Do you disconnect the negative battery terminal before any install? Other:There is another group of vehicles using class 2 data. The Oldsmobile Aurora, Buick LeSabre and Pontiac Bonneville use a flatwire or ribbon cable type connection @ the radio. This is also referred to as GM’s “dock and lock” setup. Until a harness, in my opinion a complete rewire is easiest for aftermarket head installation. Cadillac also has several models using class2 but further info is not yet available.
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA