Interesting approach. Not sure if it applies to Toyota Smart Keys but Lexus Smart Keys can still start your car with no battery inside them. I believe when there is no battery, the immobilizer functions like the chips used in standard keys that is energized by coil/induction. You hold your Lexus smart key right up to the push button and once it's energized and detected, you can start it. Found this out on an LS430 I borrowed.

If you could test it yourself on your HL, it would be good to know as then you'll have to keep your key even more secure as without the battery it is still a functioning key.

 

Yes. You can hold the smart key up to the start button and start the car so it has to be well hidden in the car. Fortunately, there plenty of good hiding places inside a Highlander. The circuit board of the start button might even fit in a second key locker if you wanted to lock that away also.

 

Hmmmm, I thought you can't lock the car with an electronic key inside? But tin foil can always fix that....

I'd say if you do go with your plan, probably attach the lock box somewhere in the rear like around the spare tire area so it doesn't interfere with suspension, drivetrain, or gas lines.

 

It's looped around a metal part in the back and then duct taped to keep it from rattling. With the battery out, the electronic key isn't transmitting. If you leave the battery in and hide the key in the back then the hatch will open because there's an antenna back there.

 

Ok I'm having a brain fart -- how do you get into the car without a key, if you lose your key??

 

The small physical key can be removed from the smart key and can unlock the driver door but it can't start the car. It's small enough to be put into a combination key locker and attached somewhere on the body of the car. I like the one with a metal cable loop because you can attach it to something and don't have to worry about it falling off.

 

There's my brain fart -- they key is outside the car hanging somewhere...

 

Not sure exactly where to put that lock box other than towards the rear of the vehicle around (or on to) the spare tire... If that is where you have in mind then try somewhere else as that is a well known place for hiding spare keys - LOL; plus there are thieves who specialty in stealing spare tires from down-under... Also, if the lock box is exposed to weather/water splashes, road salt and etc. it may be rusted shut by the time you really need to access the spare key inside, so be careful (i.e. like soooo many vehicle owners who lock their spare tire with/without "weather proof" chains/locks from theft but only to find out that their locks are rusted shut therefore unable to remove to use the spare when needed).

As for the smart key, our vehicles have a proximity sensor smart enough to know if the key fob is left "inside" the car, so the doors will not lock. With the key fob outside yet within inches to the tail gate, the rear glass and/or entire hatch can be unlocked then opened; same with the driver-side door (depends on your custom vehicle setting - all doors may be unlocked at the same time) when touching the driver-side door outside handle. I don't think anyone is thinking nor saying to hide a smart key (fob) outside of the car, as that basically is not much difference from leaving a car unlocked.