1. Identify the Problem:
* Key won't turn: This could be due to a broken key, a bent or damaged lock cylinder, a seized mechanism inside the lock, or a problem with the linkage connecting the lock to the trunk latch.
* Trunk latch won't release: This points to a problem with the latch mechanism itself, the connecting rod, or possibly a problem in the electrical system (if your model has power trunk release).
* Key works intermittently: This suggests a problem with the lock cylinder, likely dirt, debris, or wear.
2. Simple Troubleshooting:
* Lubricate the lock: Use a graphite-based lubricant (like powdered graphite or a specialized lock lubricant) to spray into the keyhole. Work the key gently back and forth several times. This might free up a sticky mechanism.
* Check the trunk release cable: If your car has an interior trunk release lever, check the cable leading from the lever to the latch. Make sure it's not broken or disconnected. You might need to access the cable from inside the trunk (if possible without the trunk opening) or from the interior trim panel.
* Inspect the linkage: If you can access the lock mechanism (often requires removing interior panels), visually inspect the linkage connecting the lock to the trunk latch. Look for broken or bent parts.
3. More Involved Repairs (requiring mechanical skills and tools):
* Replacing the lock cylinder: This is often the best solution if the key won't turn smoothly or at all due to wear. You'll need to find a replacement lock cylinder specific to your 2000 Chrysler 300. This involves removing the old cylinder, usually requiring careful disassembly and potentially specialized tools. You'll also need new keys cut to match the new cylinder. This is best tackled with a repair manual.
* Replacing the entire trunk lock assembly: If the problem lies with the latch mechanism or internal components beyond the lock cylinder, replacing the whole assembly might be necessary. This is a more involved job requiring disassembly of interior trim panels and potentially welding expertise depending on how the lock is attached to your model.
* Addressing electrical issues (power trunk release): If the power release is malfunctioning, check the fuse, wiring, and the switch itself. This could involve using a multimeter to check for continuity.
4. Professional Help:
If you're not comfortable with mechanical repairs, especially if the problem is complex or beyond simple lubrication, it's best to take your car to a qualified locksmith or auto mechanic. They have the tools and expertise to diagnose and fix the problem efficiently and correctly. Attempting more complex repairs without the proper knowledge can lead to further damage and increased repair costs.
Important Notes:
* Repair Manual: A Chrysler 300 repair manual specific to the year 2000 is invaluable. It provides diagrams, procedures, and torque specifications to guide you through the repair process.
* Safety First: Always disconnect the negative battery terminal before undertaking any electrical work.
* Parts Sourcing: Finding replacement parts for a 20-year-old car might require searching online retailers, salvage yards, or specialized automotive parts suppliers.
Remember, tackling a trunk lock repair involves some risk of causing more damage if not done correctly. Weigh the difficulty and your own skill level before attempting the repair yourself. In many cases, the cost and frustration of attempting a DIY repair outweigh the cost of professional service.
