oh yes, im quite aware of the systems integration with the head unit and the various other systems that cadillac has decided a "good idea" to make our lives miserable trying to upgrade our stuff....
BUT what they didnt expect (as well as my 92 eldorado) i got these to add to my arsinal:
which allow me to track down the circuits that are integrated to the head unit and bypass the head unit integration.... when i did the carputer install on my 92 eldorado as soon as i pulled out the radio i knew there was something "amiss" as the wires were way too small for the 12v power etc, and a lil tracing and research lead me to the primary receiver being in the trunk. after some testing of the relay system, i isolated what was "necessary" for normal car functions without having the stock receiver present. this is the whole foundation to GM's "ANTI THEFT DEVICE" by splitting up the devices into multiple parts and scattering those parts throughout the vehicle, someone cant just "steal your radio" they only would be getting the digital control system that remotes the receiver in the trunk.... P.I.T.A.
One thing I do have a problem with on the 97 install that is very much different than the 92 install is the location of the fuse panel. On the 92 eldorado, it is just inside the trunk on the left which makes it easy access, on the 97 seville, its all the way INSIDE the trunk mounted up against the back of the seat. SOOOooo if the person changing the fuses were say 250#'s and 6' tall, this would be a major problem, im 185 and 5'7" and i find it STILL a major problem as this limits where i can mount the equipment. The old sterio system will be completely removed, the fiber carpet covered trunk liner will be removed, and i might re-route the fuse panel in order to utilize the back of the seat properly.
The service manuals that i have for the 92 and 97 are pretty complete, shows the ENTIRE circuit layout, which takes away from the guesswork. Basicly, find what you want to remove, what you want to remain, and trace the circuits. The hardest part of it all, is trying to apply the schematic of the manuals to "where its at on the car" though, the locations in the schematics are relatively simple to figure out where they have mounted equipment, sometimes its pure luck finding stuff.