1. Preparation:
* Disconnect the battery: This is crucial to prevent accidental short circuits and shocks. Disconnect the negative (-) terminal first.
* Gather tools: You'll likely need a variety of screwdrivers (Phillips and possibly flathead), possibly panel removal tools (plastic pry tools are best to avoid scratching), wire strippers/cutters (if you're replacing the wiring harness), and possibly a multimeter to test the existing wiring.
* Consult a repair manual: A Haynes or Chilton repair manual specific to a 1990 Oldsmobile 98 will be invaluable. It will show diagrams of the interior and speaker locations, potentially even the removal procedure. If you don't have one, searching online for "1990 Oldsmobile 98 repair manual PDF" might yield results (though legality of some sources is questionable).
* New speakers: Make sure you have the correct size and mounting depth speakers. Measure your existing speakers before purchasing replacements. Consider speaker adapters if the replacement speakers don't directly match the existing mounting holes.
2. Accessing the Speakers:
This is the trickiest part and varies depending on the trim level and options of your car. The speakers might be located:
* In the rear deck (shelf): This is the most common location. You'll likely need to remove the rear deck panel or sections of it. This usually involves unscrewing fasteners and carefully prying the panel away using plastic pry tools. Be gentle to avoid breaking clips. Look for screws around the edges of the deck, under the rear window trim, or even inside the trunk.
* In the rear side panels: Less common but possible. You might need to remove the side panels, starting from the bottom and working your way up. Again, look for screws and clips.
* Behind the rear seat: Less likely in a 98, but possible. You would need to remove the rear seat first.
3. Removing the Old Speakers:
Once you have access, the speakers themselves are generally held in place by screws or clips.
* Screws: Unscrew these to release the speaker.
* Clips: Carefully pry the speaker away from the mounting bracket, using plastic pry tools to avoid damage.
4. Wiring:
* Disconnect the wiring harness: Carefully disconnect the wires from the old speakers. Take pictures or make notes of how the wires are connected to avoid confusion during reinstallation.
* Inspect the wiring: Check for any damage or corrosion. Replace any damaged wiring.
* Wire the new speakers: Connect the wires to the new speakers, matching the polarity (+ and -). Use electrical tape to secure the connections.
5. Installing the New Speakers:
* Mount the new speakers: Secure the new speakers to the mounting bracket using the appropriate screws or clips.
* Reassemble: Carefully put the panels, deck, or seat back in place, making sure everything is securely fastened.
6. Testing:
* Reconnect the battery: Reconnect the positive (+) terminal first.
* Test the speakers: Play some music to ensure the new speakers are working correctly.
Important Considerations:
* Patience: This process can be time-consuming and requires patience.
* Take your time: Rushing can lead to damage.
* Safety first: Always disconnect the battery before working on the electrical system.
* If you're unsure: If you're uncomfortable with any part of this process, it's best to seek professional help from a car audio installer.
This is a general guide. The exact procedure will vary depending on your specific 1990 Oldsmobile 98 model. Finding a repair manual or searching online for "1990 Oldsmobile 98 rear speaker replacement" with images might provide more specific instructions. Remember to always prioritize safety.
