To find the module:
* Consult your Cadillac Deville's repair manual: This is the best resource. It will pinpoint the location of the BCM or the relevant control unit, and show you how to access it.
* Check online forums and resources: Search for "1999 Cadillac Deville BCM location" or "1999 Cadillac Deville turn signal flasher location" on forums like Cadillac forums or general automotive repair sites. Someone may have already documented its location with pictures.
Keep in mind that replacing the BCM is usually a complex task requiring specialized knowledge and tools. It's not a simple bulb replacement. If you're experiencing issues with your turn signals or hazard lights, it's best to consult a qualified mechanic rather than attempting repairs yourself unless you are very experienced with automotive electronics.