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Car Immobilizer

2K views 2 replies 2 participants last post by  igeorge 
#1 ·
I made my own immobilizer which is activated by an encrypted LORA chip.
The bottom line is a receiver/main board with relay output, installed in the car, and a small transmitter/remote, in my pocket.
The communication is a 128 bits encryption, a military standard.
The end of this device is a contact normal open of a relay. In my car, I put it on the ignition wire.
I cut the wire which goes from the fuse to the starter solenoid and inserted the relay contacts.
If I press the remote, the relay will close(and stay close until I shut off the power), and I can start the engine. When the relay is open, the starter does not turn.
I would like to know if it is anything else, that I can cut and put in the relay.
A thief, if he gets time will easily find the relay connection.
When a new antitheft device hit the market, they will buy it, study it and they can bypass it easily. My goal is not only to put in the start system.
For example, on my 2016 MDX, if the door opens, the car automatically moves to park and I cannot drive it. So, if I put on some door sensing circuit, the engine starts, but they cannot drive. But in this case, will be harder to find out where it is the cut on the wire.
I am looking for any suggestions to insert the system that is hard to find. My remote has 4 buttons, and I can put 4 small relays, so the life of that stupid thief will be literally miserable.
Please help and come up with your solutions. I am an electronic engineer and I can modify/update my system to any suggestion.
The only place I will not put it is the fuel pump.
Admitting that I am the owner of the car, start the car and drive. If anything goes wrong with the system, and the relay opens while I am in heavy traffic/high speed on the highway, the car will stop and make a huge accident. The fuel pump circuit is a NO NO.
Thank you very much
 
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#2 ·
I'm pretty certain that every MDX since Gen1 has had a factory immobilizer as standard equipment.

I suppose have a series system (with your own immobi) affords more theft/hot wire protection, but at the same time, you are introducing additional fail points in what can be considered a functional safety system (ISO 26262.)

The factory immobilizer is designed to operate down to a pretty low battery voltage due to the drop that can be experienced on a cold crank start. How low a voltage does your relay work at?

During my years working on Ford PCMs and Honda ECUs, we always test the hell out of rapid key on/key off situations because the ECU-immobi communication has to be bulletproof.

I'm not even sure what insurance companies would do " in the event of a claim (comprehensive or collision) if they find out the "passive antitheft" in your SUV is no longer "stock."

A 2016 MDX is pretty new -- I sure hope you have full coverage.
 
#3 ·
I'm pretty certain that every MDX since Gen1 has had a factory immobilizer as standard equipment.
Mine, except the keyfob, does not have anything.

[QUOTE="I suppose have a series system (with your own immobi) affords more theft/hot wire protection, but at the same time, you are introducing additional fail points in what can be considered a functional safety system (ISO 26262.)
[/QUOTE]
I do not understand your meaning, please explain.
[/QUOTE]

[QUOTE="The factory immobilizer is designed to operate down to a pretty low battery voltage due to the drop that can be experienced on a cold crank start. How low a voltage does your relay work at?
[/QUOTE]
My relay works down to 9 volts. But it is beside the point. If the battery is low, you give a boost.

[QUOTE="During my years working on Ford PCMs and Honda ECUs, we always test the hell out of rapid key on/key off situations because the ECU-immobi communication has to be bulletproof.
[/QUOTE]
Please explain

[QUOTE="I'm not even sure what insurance companies would do " in the event of a claim (comprehensive or collision) if they find out the "passive antitheft" in your SUV is no longer "stock."
[/QUOTE]
Please explain

[QUOTE=" A 2016 MDX is pretty new -- I sure hope you have full coverage.
[/QUOTE]
I have full coverage for my car, but this is beside the point also.
If you read and try to understand between the lines and the "fine print" of my post, I was looking for suggestions to make the thief's life miserable and force him to go to the next car.
Worst come to worst, the insurance can decide that I do not have extra antitheft protection than one installed by the manufacturer. They will not deny my claim, as I left the antitheft system installed by the manufacturer in place and did not alter or disable it.
And as you said that you worked with the ECU, what is the "ECU-immobi".
I have the full electrical diagram of my car, and except for the safety inputs going to ECU and Ignition circuit, I do not see anything else. On my MDX, the only immobilizer is the keyfob.
Your experience with ECU inputs from different sensors in the car can help me by suggesting what to disable and make the engine not start, or not move to the drive position(this is valid for push buttons shifter like mine)
 
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