How does a "smart" key know the keys are not inside the car

[SpyOne]

@Joey_P

My understanding (though I’ve never tried it) is that if the car is running and the key is in it, is that the engine will cut out if you put it in gear without the key inside the car…

This seems like an improvement.

Many years ago, a writer for Car & Driver was testing a Corvette that had one of those “keyless” keys and found out the hard way that the place he hung his keys at home (right next to the garage door) was close enough to the car to allow him to get in, start it, and drive away.
“Found out the hard way” as in came out of a store, could not open the car, and only then realized that his keys were still hanging at home.

[bob_2]

@SpyOne

This seems like an improvement.

Many years ago, a writer for Car & Driver was testing a Corvette that had one of those “keyless” keys and found out the hard way that the place he hung his keys at home (right next to the garage door) was close enough to the car to allow him to get in, start it, and drive away.
“Found out the hard way” as in came out of a store, could not open the car, and only then realized that his keys were still hanging at home.

Modern cars are so hard to steal that these days the thieves burgle the house and take the keys. Best make those keys a little harder to find. One of my neighbours had a very nice Audi Quattro. Unfortunately he kept the keys on a hook in the hall.

[Rigamarole]

@Exapno_Mapcase

My car will not let me lock the keys inside. Once when we were out and I was driving, my wife wanted to leave her purse inside the car when we made a stop. The car kept yelling at us until we figured out that her key inside her purse was the cause.

Wait a sec, you have a car that yells? Now that’s innovative.

[SmellMyWort]

@Joey_P

Just to second what others have said, I can’t lock my key inside my car (2016 Accord, but my 13 accord wouldn’t do it either). I also couldn’t lock it in my trunk either. If I tried, the trunk would just pop right back open. That causes a (small) issue if you try to close the trunk the with key too close. I’ve heard reports of women pushing the trunk lid down with their purse and having it open back up.

I have theories on how it works, but I’m not sure. FTR, I’ve never tired, say, putting the key in the back seat and locking the door to see if that works.

One thing that bugs me with this, and it may be Honda specific, is that I can’t lock the doors, with the key outside the vehicle and the car running. For example, If I want to keep the car running and run in to the gas station or store my options are lock the doors OR leave the engine running. I’m not sure why it can’t be both. My understanding (though I’ve never tried it) is that if the car is running and the key is in it, is that the engine will cut out if you put it in gear without the key inside the car.

Also, just FTR, if I get out with the engine running (and my key is always in my pocket), the car beeps at me. It’s very aware of where the key is at any given time.

I’m kind of curious as to what would happen if I tossed the key out the window while I was driving. A FOAF had his Proximity motorcycle key bounce out of his saddle bag while he was riding on the freeway. He had to go back and try to find it after the engine quit.

And while we’re here, I want to mention that I LOVE my smart key. I love not having to dig around for keys (it’s the only one I carry). In winter I just bury it deep in an inside pocket in my jacket and all I ever have to do is push buttons. It’s a nice convenience.

I love the smart keys, too, but also hate that you can’t lock the car with the engine running. Or, at least on some you can’t. On our Nissan you can. Our other car is a Suzuki and on that one you can’t lock with the door button or the fob, but you can lock it with the actual key.

[Joey_P]

Now that I give it some more thought, something I haven’t tried is just pressing the actual ‘door lock’ button (with the engine running) and closing the door. That might work. That should work. I mean, I can use that button to lock the door while I’m inside the car, right. However, I don’t know how the car will react when it realizes the key is outside. It might unlock the doors (which wouldn’t make sense since the car would ‘know’ I have the ability to get back in).

[SmellMyWort]

@Enola_Gay

The potential for theft is exactly what I was getting at. So it DOES allow you to lock your keys inside the car? We’ve had a rash of crime in our area where thieves are just walking down the street and trying every parked car to see which ones are unlocked, then when they get lucky they take anything of value.

With this new smart key system, they could do the same thing by trying the little button to see if anyone has left their keys in the car.

I’m guessing a hide-a-key would be a bad idea with this type of car.

But someone else told me today that on their car, that feature only works if the keys are OUTSIDE of the car. If that is true, I’m hoping someone will chime in here and explain how that works.

sbunny8 is wrong. You can’t lock your smart key in the car and if you have the key with you in the car and the doors locked someone can’t just come up and unlock the door.

A hide-a-key might work but you’d have to test out spots furthest from where the sensors are located. They tend to be the front driver and passenger doors and then one at the trunk/hatch. So if you put the hide-a-key somewhere up by the front bumper it might be far enough away that the sensors don’t “see” it. The systems I’m familiar with have a regular metal key built into the fob so you might also be able to copy that and hide it anywhere. That will at least let you unlock the car and on some you can start the car with the regular key, too.

[Joey_P]

@SmellMyWort

The systems I’m familiar with have a regular metal key built into the fob so you might also be able to copy that and hide it anywhere. That will at least let you unlock the car and on some you can start the car with the regular key, too.

Something that annoys me with my car is that the metal key (the blade) will allow me to get in my car, but not start it. Furthermore, when I turn my car off the steering wheel locks (I can hear a motor in the column locking the wheel). If my battery were to die or I only had the key blade, moving the car would be very difficult.
I asked the Honda mechanics what I would do if I was in a position where the car died, say, in a parking spot and needed to be jumped. I can remember, back in the day, a couple of people pushing a car out of a parking spot so that the jumper cables could reach the battery. Nowadays, that might not be possible, especially if your steering wheel was turned when your shut the car off. He checked his service manual and the best thing he could come up with is ‘find longer jumper cables’. There’s no way to unlock the steering wheel without the car having power to release the lock.
ETA, I suppose you could crack the column and apply power directly to the lock, but I’d just like a way to be able to push it out of a parking spot or garage and be able to have some ability to steer it.

[SmellMyWort]

@Joey_P

Now that I give it some more thought, something I haven’t tried is just pressing the actual ‘door lock’ button (with the engine running) and closing the door. That might work. That should work. I mean, I can use that button to lock the door while I’m inside the car, right. However, I don’t know how the car will react when it realizes the key is outside. It might unlock the doors (which wouldn’t make sense since the car would ‘know’ I have the ability to get back in).

In my Suzuki the driver’s side door will unlock if I try to use the inside door lock button. I use that button to lock the doors, then shut the door (door unlocks), then use the blade key to re-lock the door.

[bob_2]

@Rigamarole

Wait a sec, you have a car that yells? Now that’s innovative.

I used to drive a truck that “yelled” at me if I opened the door without first applying the parking brake. "APPLY BRAKE"

[troub]

@SmellMyWort

sbunny8 is wrong. You can’t lock your smart key in the car and if you have the key with you in the car and the doors locked someone can’t just come up and unlock the door.

Well, it seems different cars (maybe mostly depending on age, but certainly manufacturer) act differently. But my experience is that you can’t lock the key inside the car. If you try to lock the door with the button on the outside while the key is inside, you get a loud fast repeated beeping sound and the door refuses to lock. The buttons inside allow you to lock the door. Same if you try to UNLOCK the door from the outside while the key is inside (ie, the “sitting at a stoplight” scenario). Basically, the outside buttons are disabled when the key is inside the car, which generally makes sense.

Only bit of trouble I had was if I wanted to leave the car, running, but locked, with a passenger in the back seat. I would leave the keys inside with them (because I’m not completely clear on what happens if the key leaves the vicinity of the running car). I would open the door, hit the lock button on the inside of the door, and go in. Coming back was a problem…can’t use the outside button, and guess what, the keyfob doesn’t work inside the car either, so the back seat passenger had to crawl up to the front to hit the inside door button. Similar “weirdness” if the passenger has their own keyfob in their pocket when I leave the car…they have to remember to manually lock the doors from the inside, if they want to lock the doors, and then unlock it for me when I get back. Maybe all this can be avoided if I learn that I can take my keys with me and it won’t kill the engine.

As for how it knows where the key is: I assume there are antennas all around the perimeter as well as somewhere inside the car. By measuring something like relative signal strength (or precise round-trip time of a “ping” signal, or something) to all of these antennas the computer can triangulate, potentially pretty precisely, where exactly the fob is based on its distance from each antenna.

[iamthewalrus_3]

@Joey_P

I’ve heard of people in situations like that ‘can you drop me off?’ They get into that person’s car, drop the person off, driver drives away with the car and can’t restart it later without the key. For example ‘can you drop me off (and pick me up later) at the bar/friends house/library etc?’.

My car will beep at me and flash a “Key Not Present” message if the key leaves the car while it’s running. And it will keep beeping for at least several minutes.

I don’t know if I could drive it away at that point if I wanted to, but it would be very difficult to do so accidentally.

[Voyager]

My Prius won’t let me lock my keys in the car, as I found out one day when they slid out of my pocket. It also automatically locks the doors when I put the car in Drive or Reverse. And it turns on the interior lights when I get close to the car, which sometimes happens when I’m walking the dog. But it requires my hand on the handle to unlock.

I haven’t tried locking the keys in the trunk, but I doubt it would let me.

[Driver8]

@Voyager

My Prius won’t let me lock my keys in the car, as I found out one day when they slid out of my pocket. It also automatically locks the doors when I put the car in Drive or Reverse. And it turns on the interior lights when I get close to the car, which sometimes happens when I’m walking the dog. But it requires my hand on the handle to unlock.

I haven’t tried locking the keys in the trunk, but I doubt it would let me.

Ditto. The interior light thing when walking past the car is a little creepy.

Actually, this is a feature that really works well, and is really reliable. I’d love to find something similar for my house front door. There do appear to be some Bluetooth and RFID products on the market, but the reviews make it sound like a hassle, with unreliable syncing and waiting around a lot. I’d really like something that worked the same as the car and used the same underlying technology.

[Spiderman]

@Driver8

Ditto. The interior light thing when walking past the car is a little creepy.

Actually, this is a feature that really works well, and is really reliable. I’d love to find something similar for my house front door. There do appear to be some Bluetooth and RFID products on the market, but the reviews make it sound like a hassle, with unreliable syncing and waiting around a lot. I’d really like something that worked the same as the car and used the same underlying technology.

Why not just install a regular motion sensor light?