1999 Cadillac Serious Problem

Some of these caddis have stumped me also, and I have pretty much seen everything. What I would reccomend is to plug the stock deck back in and undo anything else done to accomodate the new deck, and see if everything works normally again. If not, we can take it from there.

If so, I would strongly consider leaving the stock deck wired up, but extend the critical wires (power, data etc.) and relocate the factory deck to the trunk. Run wires from the speakers to the new deck and this way you have "fooled" the vehicle into not even knowing you swapped the deck out. Keep in mind if it's a bose system (99%) sure it is, you will need to swap speakers, or depending on how many speakers are in this system to re configure the ohms load to a minimum of 4 ohms per channel, if adding an amp you'll be ok @ 2 ohms per channel.

I had a situation once with a 96 seville (w/bose) that had serious current draw problems after doing a simple deck swap/ amp bypass. I was able to get that under control after several days BUT, the 99 system is different ( some similarities)so other systems in the vehicle are involved. The  96 was only a 4 speaker bose system (amazing all that insane wiring and modules for just 4 speakers) but I had to swap those out for 4ohm aftermarket speakers as well.

Now the other option might be you have a bad OR the wrong data module..these peices are fairly new to the market and might have bugs that need to be addressed. You didn't mention if this was a bose but I will assume it is. I have seen the diagram for that system along with the data lines and it's pretty hairy just for a sound system. I don't know what Mr. Goodwrench was on when doing this but best to leave it alone by relocating the factory deck IMO.

Good Luck