Here's a general guideline:
1. Preparation:
* Gather Tools: You'll need a panel removal tool (plastic pry tools are ideal to avoid scratching), screwdrivers (Phillips and possibly flathead), wire strippers/cutters, electrical tape or butt connectors, and possibly a multimeter to test speaker wiring. It's helpful to have a flashlight.
* Consult a Wiring Diagram: Find a wiring diagram specific to your 1989 Cadillac DeVille. This will help you identify the speaker wires and avoid mistakes. Online resources like Haynes repair manuals or online forums dedicated to Cadillacs might be helpful.
* New Speakers: Ensure you have the correct replacement speakers. Note the size and mounting depth of your old speakers before purchasing replacements to ensure a proper fit.
2. Accessing the Speakers:
* Rear Deck/Shelf Removal: This is usually the most challenging part. The rear deck (the panel behind the rear seats) likely needs to be removed. This often involves:
* Unclipping: Carefully use panel removal tools to pry off the trim pieces around the rear deck. Start at the edges and work your way inwards. Be gentle to avoid breaking the plastic clips.
* Removing Screws/Bolts: There may be screws or bolts holding the deck in place. Locate and remove these.
* Disconnecting Connections: There might be antenna connections, lighting connections, or other wiring harnesses connected to the rear deck. Gently disconnect these. Take pictures before disconnecting to help with reassembly.
* Speaker Location: Once the deck is removed, you'll find the speakers. They are usually mounted in the rear side panels.
3. Speaker Removal and Replacement:
* Disconnect Wiring: Disconnect the wiring harness from the old speakers. Note the color coding of the wires for proper reconnection later.
* Remove the Old Speakers: The speakers may be screwed into the panel or use some other type of mounting mechanism. Carefully remove them.
* Install New Speakers: Mount the new speakers in the same location as the old ones. Make sure they are securely fastened.
* Reconnect Wiring: Carefully reconnect the speaker wires to the new speakers, matching the color coding. Use butt connectors or electrical tape to secure the connections.
4. Reassembly:
* Reconnect everything: Reconnect the wiring harness, antenna, lighting, etc. to the rear deck.
* Reinstall Rear Deck: Carefully reinstall the rear deck, ensuring all screws and bolts are tightened. Push the trim pieces back into place.
Important Considerations:
* Patience is Key: Removing interior panels can be tricky. Take your time and be gentle to avoid breaking clips or damaging the panels.
* Take Pictures: Take pictures at each step of disassembly to help you remember how everything goes back together.
* Speaker Depth: Ensure the new speakers fit within the available space in the door panel. You might need to use speaker spacers if the new speakers are deeper than the old ones.
* Wiring: If the wiring is damaged or brittle, it's a good time to replace it.
This is a general guide. For precise instructions, consult a repair manual specific to your 1989 Cadillac DeVille. Remember safety first – disconnect the battery before starting any electrical work. If you're not comfortable with this task, consider taking it to a qualified auto mechanic.
