I've got a '96 C4 Corvette that has the factory optioned "Pass-Key System", which is/was meant to unlock the car automatically when you got near it, lock it when you walked away - aswell as provides Central Locking and Remote boot hatch buttons.
The problem with this is, Chevrolet do not manufacture these fobs anymore and I cannot locate any suitable replacements short of spending $1000 on a NOS Example. I have 1 working Keyfob.
I could care less about the proximity stuff, I just want to be able to remotely lock and unlock the vehicle. I don't want to install an aftermarket system in the vehicle either, I'd like to leave it completely stock.
I've got basic SDR knowledge and to my knowledge it should be using RF - my very high level, rough draft plan would be to identify the frequency and capture what it's sending to the vehicle and get some sort of an understanding as to how it works, then emulate that via an Arduino RF Transmitter circuit. I'll worry about making it Keyring-able later, this is purely a proof of concept at this point.
At this point I would love any guidance,input or feedback from anyone who has knowledge in these areas or may have done something similar - links to further reading and learning resources would be great. I've started researching car key fob and access system in general, a few good whitepapers like this have been a good launch point.
That's good starting point. Find what frequency and what kind of messages your key is using. Depending how the system is built, it can be doable or not. First thing you have to verify, if your car is willing to start without presence of that fob (let's say you open the doors and then remove battery from fob). If yes, you have some options.
Yes, The key uses what is effectively an SMD Resistor on they key as a primitive immobiliser - if the resistance matches what it's expecting, it'll start.
Years ago I was talking to a Microchip tech rep. He was explaining the rolling code approach. If it doesn't create a risk, I would open the functional one and see what devices are in there.
If it is Microchip I would go on their forum and ask the question.
Also see if you could find someone who can program them, Perhaps through a Corvette website.
I meant if the car is happy without that "pass key system" you mentioned. If your remote is bi-directional, it's getting difficult.
Are you looking for to emulate, because you're scared to loose the only fob you have or...?
I Lose things, car key fobs included. I currently do not carry the fob with me, keys only - on the off chance I misplace the fob I don't want to fork out that much for a replacement - I've only got one, plus I'm in Australia so the chance of finding one locally is nil, so getting one online + shipping + import tax + exchange rate - its just not worth it.
So IF I can make a basic fob, purely for remote central locking/hatch - that'd be super.
The current fob has a broken housing (Came that way - 3D printing a replacement once my new printer arrives) so I'll be doing more research on the components used in the OEM fob when I get the chance.
Many new cars have a system that can replace your garage door remote, making the door open/close by a button on the dash. Perhaps there is a way you could learn from them.
OK - I Appreciate the clarification, I was hoping that the technology may have been fairly primitive, therefore making it easier for me to replicate however, it would seem this is not the case then. I'll still give it a shot but, it would seem the odds are stacked against me. Also you are correct, if it's possible by an amateur like myself, then alot more corvette's would go missing
