[bejoy]

Originally Posted by theexperthand

Locked Out:

I called up my friend who is in Bangalore (who, fortunately, had my house key with him) and he took the spare key from my house and after putting his mobile on speaker, unlocked the car couple of times. I also put my phone on speaker and kept the phone near the front door and voila, after a couple of times my friend clicked the unlock key, we heard the sweet music of the car unlocking

--Anoop

Since it is coming from a bhpian and it is not on April 1st, I assume it worked

I can think of only of some weird combination of RF mixing (Phone's operating band/internal clock/etc.) and the FOB signal and some resultant harmonic frequency transmitted as voice and then the reverse process happening at the receiving phone. Same phone model at both ends? or same chipset? Remotely possible. (no pun intended)

And yes, it may not happen always. Anoop, please take a video of this, would love to see in action!

[Govind]

Originally Posted by Nishith

+1 on the video regarding the Locked-out instance.

Would be great if you can capture this on a video and post it. I always rubbed this off assuming it would not work.

Thanks,
Nishith

Just out of curiosity:

It should be possible to lock/unlock by playing that video as well? So if we record the beep/signal on the phone while someone locks/unlicks the car, the person can later replay the recorded content and do lock/unlock?

As far as I know, the keyless entry mechanism works in a dynamic challenge - response mechanism which must not unlock the car simply without a proper response for the dynamic challenge.

/Govind

[venkyhere]

What must be happening is "aliasing" through subsampling+supersampling on the signal. The phone mic and speakers operate over <20Khz range, and remote keyfob communication must be somewhere within 100Mhz and 1000 Mhz. But some 'aliasing' can happen, if lucky (google "signal aliasing").

In layman terms, it's like how at certain speeds, if observed from a parallel vehicle, a car's wheels appear to slowly moving in reverse OR if we pay attention to the barricade guard rail alongside a highway, it's poles moving backwards at certain speeds, then stationary at further speeds, an even forwards at even higher speeds.

Only a blind guess, since the radio freq of communication b/w a car's keyfob and the audio frequency band of human hearing are certainly disjoint from each other.

[RedTerrano]

Originally Posted by theexperthand

Locked Out:

Ok I am trying to understand what exactly happened here.
Step 1: How did you get locked out? Was the key inside the car? If yes, how did the doors locked?

[theexperthand]

Wow, so much discussion on this

I am not quoting individual posts, but will try to answer the questions:

No, my car does not have iRA. It comes with connectnext, which is not at all useful.

My friend who did the unlock from Bangalore has an iPhone and I use a Poco X3.

The Harrier remote has 4 keys and one of them only unlocks the boot. I pressed the key, opened the boot and kept the key inside, and then closed the boot door. It is really nice that Maruti, Hyundai, Honda, and many others offer a failsafe mechanism against blunders like this. I Hope Tata also implements it.

I do not have the technical know-how to understand how it works, but I am thankful that this method has worked twice for me.

The first incident happened almost 15 -16 years back. The car was a first-generation jelly bean Maruti Zen with aftermarket autocop central locking. I parked the car in Chennai and came to Bangalore with the key. Android\Feature mobiles were not common at that time and both me and the party at the other end were using normal mobiles (In my case, most probably either Nokia or Motorola - don't remember the details).

In the current instance, my friend who took the key is using an iPhone and I am using a Poco X3.

I will try to make a video of this once I am back to Bangalore (I will see if I get third-time lucky )

--Anoop

[Siddarth_Ramani]

Can anyone explain the science behind this? I was in the same situation some years back with first gen swift facelift with Autocop central lock. It didn't work for me back then.

[Samurai]

Originally Posted by PreludeSH

Really ? Does the keyfob emit frequencies that match the human frequency range ? Even then only a small band in the human voice frequency is passed by modulating to the radio frequencies and converting back to what was originally passed. If the keyfob is using higher radio frequencies, it cant work.

May be Nyquist principle has ceased to exist...

Unless the keyfobs have started working below 4Khz frequency, I can't fathom how this can work. The ADC on the mobile phone will only sample at 8000 times/sec. So it can't capture higher frequencies than half that rate (4k).

If they sample at higher frequencies, say 16K... twice the number of data has to be sent across. To capture a 10MHz signal, the phone has to send across 2500 times more data compared to a regular speech. Just saying...

[beast_within]

Originally Posted by theexperthand

The Harrier remote has 4 keys and one of them only unlocks the boot. I pressed the key, opened the boot and kept the key inside, and then closed the boot door. It is really nice that Maruti, Hyundai, Honda, and many others offer a failsafe mechanism against blunders like this. I Hope Tata also implements it.

--Anoop

Yesterday I replicated the scenerio in my 1st Gen Harrier XZ. When I shut the boot door, the car started honking, hazard lights came on and all 4 doors got unlocked by themselves. Tried twice to lock the smart key inside the boot and same results.

Having said that, I can lock the smart key inside the boot by following these steps

1. All doors are already unlocked position.
2. Keep one smartkey inside the boot.
3. Shut the boot
4. Lock the car using the remote button on the spare smart key.
5. Car gets locked with smart key inside the boot

[irdevanand]

Originally Posted by beast_within

Yesterday I replicated the scenerio in my 1st Gen Harrier XZ.

1. All doors are already unlocked position.
2. Keep one smartkey inside the boot.
3. Shut the boot
4. Lock the car using the remote button on the spare smart key.
5. Car gets locked with smart key inside the boot

Now can you please run to the next street along with the spare key and try to unlock using the phone-to-phone method So much curiosity around this thread now and all of us are hooked up to know how it works.

Regards
Dev

[sourabhzen]

Originally Posted by beast_within

Yesterday I replicated the scenerio in my 1st Gen Harrier XZ. When I shut the boot door, the car started honking, hazard lights came on and all 4 doors got unlocked by themselves. Tried twice to lock the smart key inside the boot and same results.

Having said that, I can lock the smart key inside the boot by following these steps

1. All doors are already unlocked position.
2. Keep one smartkey inside the boot.
3. Shut the boot
4. Lock the car using the remote button on the spare smart key.
5. Car gets locked with smart key inside the boot

Try unlocking only the boot, keep your key-fob inside and shut the boot. See if it unlocks then. Keep the spare key nearby (not close to the car). Let us know the results.

[beast_within]

Originally Posted by sourabhzen

Try unlocking only the boot, keep your key-fob inside and shut the boot. See if it unlocks then. Keep the spare key nearby (not close to the car). Let us know the results.

Yes, did exactly the same. Unlocked only the boot. Kept the smartkey inside and then shut the boot door. Car honked and all doors got unlocked. The other spare smart key was out of range.

[anshu1101]

Originally Posted by Leoshashi

+1. I thought it was a thing of the past with these modern key fobs. For example in my XL6, if you keep the fob inside and press the lock request switch on door handle, it emits a long chime and won't lock itself. Even if you use second fob to deliberately lock the primary fob inside, it won't happen.

Ditto in my Hyundai Tucson. If I try to lock the car using the button on the request sensor, and have left the key inside the car, the car would emit a long chime and the doors will not get locked.

[Torq]

Originally Posted by ChiragM

Trust Tata to not offer something this simple in a 20+L car. My i20 also gets this. I am sure almost every other car in the market does.

My 2017 Tiago and 2019 nexon don't lock if the key fob is inside. OP may have just unlocked the boot and hence, everything stayed locked.

[abirnale]

Originally Posted by beast_within

Having said that, I can lock the smart key inside the boot by following these steps

This basically is just soft-disabling the key left inside using a spare key. It happened all the time with my old XUV and the new one too. If you keep the key inside, you just can't lock the car without using another key remote, period. if you use the door request sensor, the car would chirp/ honk and tell you that locking failed. But when you keep one key inside and the other is used to lock, the key inside is temporarily rendered disabled.

[Strider24]

Originally Posted by BrakeDancer

Re getting locked out of the car. Damn. That's a nightmare. But this is the first time I've heard of the workaround you did to get it unlocked! Sounds interesting. The 5th Gen City has a tech whereby even if you put your keys inside the boot and close the boot accidentally, it doesn't close, and gives out a warning sound indicating that the keys are in the boot. It's a very commendable piece of tech and more car makers should make this available, instead of the standard gimmicks we get in the name of technology.

My 11 year old Corolla Altis too does this. My wife frequently tries to lock the car with keys inside and this feature help always.

On the other hand, this trick is amazing. I never knew this can be done. Thanks for sharing.