1. Check the Fuses: This is the easiest and first step. Consult your owner's manual to locate the fuse box (usually under the hood or in the interior, often near the driver's side). Look for fuses related to the power trunk release, power locks, or accessories. Check for blown fuses (a broken filament inside). Replace any blown fuses with fuses of the same amperage rating.
2. Check the Trunk Release Switch (In-car button): The button itself could be faulty. Try carefully pressing and holding it for a longer duration (sometimes a sticky switch needs a more firm, sustained press). If you have some electrical knowledge, you could carefully inspect the switch wiring for loose connections or damaged wires. However, replacing the switch is often simpler than repair.
3. Check the Wiring Harness: The wiring connecting the in-car button, the remote receiver (if it's a separate unit), and the trunk latch mechanism can become damaged, corroded, or disconnected. This is usually the culprit. You will need to carefully trace the wires from the in-car switch to the trunk latch and check for:
* Broken wires: Look for any visible breaks, fraying, or cuts in the insulation.
* Loose connections: Check all connectors along the way for secure connections. Wiggle them gently to see if any are loose.
* Corrosion: Look for corrosion at connectors; clean them with contact cleaner if needed.
* Routing issues: Sometimes wires get pinched or rubbed against metal parts during car movement.
Accessing the wiring is a bit involved: You will likely need to remove some interior panels (usually around the trunk release button and potentially some parts in the trunk itself) to fully access the wiring harness and the latch mechanism.
4. Remote Control Unit: If the remote also fails, the problem may be the remote control receiver or its associated wiring. These are more difficult to diagnose and repair.
5. Trunk Release Solenoid/Actuator: This is the electric motor in the trunk latch mechanism. It receives the signal from the in-car button or remote and unlocks the latch. A faulty solenoid will require replacing the entire latch mechanism. It's unlikely to be this, however, given the key still works.
Important Considerations:
* Safety First: Disconnect the negative battery terminal before working on any electrical components.
* Wiring Diagrams: Obtain a wiring diagram for your specific 2000 Buick LaSabre. This will greatly help in tracing the wiring harness. You may find a diagram online or in a repair manual.
* Professional Help: If you're not comfortable working with car electrical systems, it's best to take your car to a qualified mechanic or auto electrician. Improper wiring can lead to further damage.
Start with the simplest checks (fuses) and work your way through the list. The wiring harness is the most likely culprit but also requires the most effort to inspect and repair.
