Your best approach is a multi-pronged strategy:
1. Consult the Owner's Manual: While it may not pinpoint the relay *exactly*, it might give you a general idea of fuse box locations. Relays are often located near fuse boxes.
2. Examine the Under-Dash Fuse Panel: This is the most likely location. Look carefully for a panel with several relays. They're usually square or rectangular components. Many are labeled, but not always clearly. *You might need to refer to a wiring diagram (see step 4)* to identify the correct one.
3. Check the Underhood Fuse/Relay Center: Some vehicles have a secondary fuse/relay center under the hood. Check this area as well, though it's less likely for the blower motor relay.
4. Find a Wiring Diagram: This is the definitive method. You can find wiring diagrams for your specific 1988 Cadillac Brougham online through resources like:
* AutoZone, Advance Auto Parts, or similar: These auto parts stores often have free online repair manuals (sometimes requiring registration). These manuals often include detailed diagrams.
* Repair Manuals (e.g., Haynes, Chilton): These offer comprehensive repair information, including wiring diagrams.
* Online Forums (e.g., Cadillac forums): Enthusiast forums dedicated to Cadillacs might have someone who has tackled this before and can share their experience or even a photo.
Important Note: When working with electrical components, always disconnect the negative battery terminal before starting any work. This will prevent accidental short circuits and protect you from injury. If you're not comfortable working with car electrical systems, it's always best to seek professional help.
