1. Check the Obvious:
* Fuse: Locate your owner's manual to find the fuse for the trunk release. Check if it's blown. Replace it with a fuse of the same amperage if necessary. A blown fuse indicates a short circuit somewhere in the system.
* Switch itself: Carefully inspect the switch on the instrument panel. Look for any visible damage, cracks, or debris obstructing it. Try pressing the switch firmly and repeatedly. Sometimes, a little cleaning might help restore functionality. (Use compressed air to blow out any dust or debris).
* Remote Keyless Entry (RKE): Try unlocking the trunk using your key fob's trunk release button. If the remote works but the switch doesn't, the problem is likely isolated to the switch itself or its wiring. If the remote *doesn't* work, the problem is further upstream (possibly a main fuse, the RKE system, or the car's central locking system).
2. Test the Circuit (Requires Basic Electrical Knowledge):
* Voltage test: With the ignition on, you'll need a multimeter to test the switch. You'll need to locate the switch's wiring harness connector (this might require some panel removal and consulting a wiring diagram – available online or through a Lexus repair manual). With the multimeter set to DC voltage, test for voltage at the connector's wires when the switch is pressed. If there's no voltage, the problem could be the switch itself, a broken wire in the harness, or a problem with the car's electrical system upstream from the switch. If there *is* voltage at the connector but the trunk doesn't open, the problem lies further down the circuit (e.g. the trunk latch mechanism, wiring to the latch, or the latch mechanism itself).
3. More Advanced Troubleshooting:
* Wiring harness inspection: If the voltage test reveals a problem with the wiring, carefully inspect the harness running from the switch to the trunk latch. Look for any cuts, pinched wires, or corrosion. Repairing a damaged wire involves splicing in a new section of wire with proper connectors.
* Trunk latch mechanism: If the wiring is good and you have voltage at the latch, the problem could be with the latch itself. This is often a more involved repair. You might need to access the trunk latch mechanism (possibly requiring interior panel removal) to test it directly or replace it.
* Central Locking Module: In some cases, problems with the central locking module can affect the trunk release. This requires more advanced diagnostic tools and potentially professional help.
4. Seek Professional Help:
If you're uncomfortable with electrical work or you've tried the above steps without success, it's best to take your Lexus to a qualified mechanic or Lexus dealership. They have the proper diagnostic tools and expertise to identify and fix the problem accurately and safely.
Important Note: Always disconnect the negative battery terminal before working with any automotive electrical system. This will prevent accidental short circuits and damage to your vehicle's electrical components. Referencing a wiring diagram specific to your Lexus ES 300's year and model is crucial for accurate troubleshooting. These diagrams are often available online (some are free, others require purchase) or through a repair manual.
