1. Preparation:
* Gather Tools: You'll need a panel removal tool set (plastic pry tools are best to avoid scratching), a Phillips head screwdriver, possibly a 10mm socket (for some models), and your new speakers. Have a clean workspace.
* Disconnect the Battery: This is crucial to prevent electrical shorts and potential damage to your car's electronics. Disconnect the negative (-) terminal first.
* Consult a Repair Manual: A repair manual specific to your 300M's year is highly recommended. It will provide detailed diagrams and instructions specific to your model. Haynes and Chilton manuals are readily available online and in auto parts stores.
2. Accessing the Rear Speakers:
This is where the biggest variation occurs depending on your 300M's model year and trim level. Generally, you'll need to:
* Remove the Rear Side Panels: This usually involves carefully prying off the plastic panels covering the rear speakers. Start at the edges and work your way around, gently applying pressure with the panel removal tools. There may be clips or screws holding these panels in place; the repair manual will show you their locations.
* Remove the Speaker Covers: Once the side panels are off, you should see the speaker grilles or covers. These are often held on by clips or screws. Again, carefully remove them.
3. Replacing the Speakers:
* Disconnect the Wiring Harness: Once the speaker is exposed, carefully disconnect the wiring harness connector from the back of the old speaker. Take a picture or note the wire positions before disconnecting to ensure proper reconnection.
* Remove the Old Speaker: The old speaker is usually held in place by screws. Remove these screws, and carefully remove the old speaker.
* Install the New Speaker: Mount the new speaker in the same location. Ensure the speaker is properly seated. Secure it with the screws.
* Reconnect the Wiring Harness: Carefully reconnect the wiring harness to the new speaker, matching the wire colors to your notes or photo.
* Reassemble: Carefully reinstall the speaker cover, rear side panels, and any other parts you removed.
4. Testing:
* Reconnect the Battery: Reconnect the positive (+) terminal of the battery.
* Test the Speakers: Play some music to ensure the new speakers are working correctly.
Important Considerations:
* Speaker Size: Check the size of your existing speakers before buying replacements. Different 300M models might have different sizes.
* Wiring: If you are upgrading to speakers with higher power requirements, consider upgrading the wiring as well. Thin gauge factory wiring may not be able to handle the increased current draw.
* Speaker Depth: Be sure to measure the depth of your new speakers. Some aftermarket speakers might be too deep to fit properly.
This is a general guide. Always refer to a repair manual for your specific 300M model year to avoid damaging your car. If you are uncomfortable performing this task, it's best to take your car to a qualified mechanic.
