How does one troubleshoot the trunk lid opener release switch located on drivers side instrument panel in a Lexus ES 300.?

Answer 1

If you don't hear a small click of a relay behind the dash when pushing the trunk release switch, check to see that the cancel button in the glove box (left side) is not activated. This will disable the remote trunk release. It should normally be pressed in to allow the trunk release button on your dash to work, and left out to deactivate trunk lock controls for higher security. Also note the service manual refers to the trunk as the "luggage compartment door" if you are trying to look for the details in the service manual schematic. At this point you should know that Lexus had a design defect in the wire harness at the left trunk lid hinge. Flexing the cable when the lid opens and closes, after many years, tends to fatigue the conductors in the wires because there wasn't enough slack. They tend to break one-by-one and be intermittant. Some control the license plate lights, tail & stop lights, trunk release, etc., and may cause strange things to occur in the electrical system when other things turn on, like when the brakes are applied. One way to test the latch is to have someone slowly open the trunk lid while pushing the trunk release switch repeatedly. If it starts to work in a certain position, then you found the problem. This test is not guaranteed, but it's quick and saves time because you don't have to disassemble anything. Inspect the wire harness as it goes through its motion and there will probably be a suspicious sharp bend point close to the main harness. This is a problem area, and to repair, you will have to strip all the tape and wire conduit carefully from the lid hinge to the main wire harness it connects to. Eventually, you should find one or two limp wires at the sharpest bend point. They will have to be cut, stripped and soldered, or apply crimp terminals or equivalent. Once fixed, tape back up allowing for more free movement so that no point has excess stress on it; no sharp bends. To inspect the solenoid at the lock directly.... remove the panel on the inside of the trunk lid. This is held in by push pins which can be gently lifted up with a flat blade screwdriver and reused later. The plug to the solenoid, or motor as it is called in the manual, can then be squeezed to release it. This exposes two terminals. The one towards the front (blue) is terminal 1 going to the motor. The other goes to a switch. Do not test by applying power to the position switch located in the motor assembly. Only apply test voltage to the pin which went to the blue wire for the latch motor. Terminals are accessible with probes. The motor is grounded to the lid, so you have to ground the negative side of your test power source to the car body. If you can't access the terminals, two bolts hold the trunk release solenoid mechanism to the trunk lid. You'll have to detach the emergency trunk release arm and keyed trunk release arm from the solenoid mechanism. You can then apply 12V to the solenoid connector terminal going to the blue wire. If the solenoid functions when power is applied, the problem will be in the wiring between the trunk lid and dash area. Removal shouldn't be necessary unless you really have to replace the assembly. Check the fuse associated with this control. On the 2001 model it is fuse number 38 in the fuse panel just behind the coin tray. Fuses may control power to several devices, so if other things are not working, the fuse is more likely blown. However, a blown fuse may indicate other power problems and is likely a symptom and not the cause. Good luck if the fuse is blown. Replace once and hope, but make sure the easy steps above aren't At Fault first. These instructions are believed to be applicable to at least model years 1997 through 2001 inclusive.