Best answer yet!

 

Hi mcfly, thanks for the analysis. I do have a couple questions though. Are you saying that the fob actually sends out an audio tone? I would have thought (I've been wrong many times before) it would either transmit a radio signal or infrared, but I've been unable to find technical specs for the fobs. Could you share where you found this?

Also, about remotes being able to block the fob signal and prevent the car from locking. I'm not sure I understand; since the fob doesn't send a "lock" signal, what is masked? The car locks when it detects the lack of fob transmission, so how would a signal being masked or blocked keep it from locking?

 

An audio tone is a RF signal. If you remember back in the day, this is how TV remotes worked. Our TV remote just happened to be the same frequency as the dogs chain, so whenever she came into the den and plopped down on the floor the channel would change! BAD DOG! Technology has improved some since then. RF signals are much higher. Beyond our hearing. Imagine if you will what the world would be like if we could hear everyone's key fobs going off. Goodness. Infra red would be, well, it just wouldn't work. Consider if you will the garage door opener. That little electric eye at the bottom of the door that stops it from closing if you walk in front of it, that is infra red. If must have a direct line of sight in order to work. RF does not. Needs a transmitter and a receiver.

Now, that other thing. The door bell. I saw this demonstrated. I believe what is happening is the door bell remote emits a RF frequency the either amplifies or cancels the sine wave (the RF signal) being emitted by the key fob. Kind of like a jamming device James Bond would use. Or Captain Kirk. By changing the sine wave the key fob emits you are in effect changing it's frequency. The receiver on the car that would pick it up and open the doors does not recognize it. So, if you park your car, hit the button while someone else is pressing their door bell remote (hoping to steal your car), the car won't lock. Now, I imagine this will not work with every door bell or with every car. Or even any car. I can neither confirm or deny. I just thought it was interesting. And I've probably confused EVERYONE! Sorry folks. This really is a silly thread. But, what else are we gonna do. Replace our ball joints?
Class adjourned.

 

You have an interesting way of explaining your concepts. If I may add/detract/distract what may you..

1. The remotes of yesterday worked on ultrasonic tones (above human hearing levels) and your dog's tags may very well have been able to change the channel but it was due to a harmonic of the frequency of the remote and it's receiver.

2. All things in the spectrum are waves. Be it Radio, visual or audible. All of these waves need a "transmitter" and "receiver". The difference is Radio Frequencies (RF) are caused by electromagnetic excitation (electrons), Audio Frequencies are caused by percussion and vibration through a substance such as air or water (doesn't travel in a vacuum), and light waves are photons. While both photons and electrons travel at the speed of light (and vacuum i.e. space), audio waves travel at the speed of sound. You can not hear RF or light. You may hear a buzz created by vibrations by an electromagnetic force but this is not hearing RF.
- RF needs a transmitter like a radio station and a receiver like your radio
- Audio Waves need a transmitter like your mouth and a receiver like your ears
- Light waves need a transmitter like the sun and a receiver like your eyes. Just like that IR LED in your garage door opener sensor. It has a transmitter (the LED) and a receiver (the light sensitive diode).

3. In order for the Garage door opener or doorbell transmitter to stop your key fob from locking your door there has to be a few things happening here. One, both the key fob and the doorbell transmitter have to be on the same frequency or some harmonic of that frequency. Two, the jamming transmitter (doorbell transmitter) has to be very powerful (wattage) or has to be very close to the receiver (car). The other scenario is the Key fob has to be very far away and of lower power than the jammer. Three, be very lucky!?

 

I actually started typing all that. About the spectrum and sound and uhf and then smacked myself in the head to remind myself I'm not being graded for any of this. Those days are over. THANK GAWD. So, what have we learned here? You cannot unlock your car with your phone. And keep the dog on a nylon leash.

 

I hear ya! Too many years as an instructor I suppose. I got to be the one to do the smacking back then.

 

If anyone is interested (or is unable to sleep) here is the patent that explains the PKE system used in the 93-96 Corvette

http://www.google.com/patents/US4942393

http://www.google.com/patents/US5319364

 

If i put aluminum foil in my hub caps will it (foil) a radar detector? Oh never mind my 93 dosent have hub caps! Happy Easter yall

 

So rf and infrared are both forms of electromagnetic radiation and audio tones are, as you would think, vibration of some medium. All waves, but to my layman's mind, not the same things. I often wish I had taken more physics/chemistry classes back when I had the energy. Thanks both of you for the info.

As for some remote being able to block a lock signal to your car, I totally see how this could happen; but I would think irrelevant to a C4 discussion, since there is no "lock" signal to block.

 

Correct. The car is looking for an absence of signal from the fob in order to lock the doors. However, someone could spoof or copy the signal of your key fob and the car would think your fob is in range again and unlock.

There would still be the issue of starting the car as they would not have the key for the ignition. VATS is a whole other issue in itself.

 

No.. you have to wear the foil as a hat to stop the RADAR waves from cooking your brain.

 

So there was no PKE available for the 1990 convert?

 

There was no GM option for KEYLESS ENTRY in '90 - it could be added using a GM accessory package that included some alarm options "in addition to" the GM TDM/VATS etc. but wasn't PKE.

PKE for me is PROXIMITY so the answer is I guess NO - NEVER

 

Thanks for the quick reply. Saved me a lot of searching.
JR

 

If a person had an ordinary GM key cut to match the VATS key, and the VATS system is disabled, will the ability to turn the key be affected? Experimenting with my '90, I had a key cut to exactly match the VATS key, minus the resistor. The key will go in, but is unable to turn. Does the resistor pellet on the key have anything to do with locking the cylinder?
The key was cut by a professional locksmith and appears dead on.

 

I disabled my VATS on my 93 a few years ago. I had a spare key made at Walmart without the chip and never had a problem. i cant see the chip stopping cylinder from turning. When i had problems with VATS chip it would turn just wouldnt turn over. Dave

 

If the length of the blade is an exact match to a VATS key then there's an issue with the "mechanical cut" done by the shop. If the key was cut on a "letter blank" key that only matches the key-way then the blade isn't long enough for the key cuts to see the pins/tumblers.

VATS key blade is maybe 37.5mm +/- from head and a "letter blank" is something closer to 30mm +/-. The effective length of the 6 cuts is the same but overall length wouldn't allow function.

Generally a "work-key" is the only key done less the resistance feature and is brass. If VATS is disabled a key with any resistance feature would work if the mechanical cuts were correct. The "work-key" is much softer material and I'd think not a good choice for everyday use.

 

Well I have a couple of VATS keys coming in and we'll see if the length difference will solve the issue. My wife "cleaned up" my area and I haven't seen the spare keys since.

 

If you did have a working factory system and locked your fob inside with the keys, you can sometimes unlock the car by rocking it, as this (movement) is what makes the fob transmit the code to unlock the door(s).[/QUOTE]

It operates on a radio frequency. It does have an unlock button (Pass side only) but only works if you have turned off the auto unlock/lock on the car thru the fob. I think my neighbor thinks I had "lost it" but rocking the car does unlock the doors if it is in the auto mode if the keys are visible to the antenna. You have to let the fob "go to sleep" for a minute or so first! I think GM should have spent more time on the Opti instead.

 

It operates on a radio frequency. It does have an unlock button (Pass side only) but only works if you have turned off the auto unlock/lock on the car thru the fob. I think my neighbor thinks I had "lost it" but rocking the car does unlock the doors if it is in the auto mode if the keys are visible to the antenna. You have to let the fob "go to sleep" for a minute or so first! I think GM should have spent more time on the Opti instead.[/QUOTE]

The unlock button for the pass door always works, same as the hatch button (if you have one).