Fingerprint Start, Immobilizer Help

Discussion in 'Accord Tech' started by Jayson, Oct 27, 2019.

  1. Jayson

    Jayson Member

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    Any electrical gurus that might be able to help me with a Raspberry Pi controlled immobilizer bypass?

    (Raspberry Pi's use 3.3 Volt logic to control things, which I can link to relay modules capable of manipulating the 12 Volt systems in our car.)

    I have been integrating my Accords features into a Raspberry Pi. This started as just a curiosity and I am learning about electrical and Linux+Python on the Raspberry Pi as I go.

    I installed a fingerprint reader in my car (left side of steering wheel where the cruise control button is) that is controlled by the Raspberry Pi. Using this fingerprint reader along with a Python script, I can use the fingerprint reader to attempt to start the car.

    However, just like a remote start system, unless the key is present to satisfy the immobilizer system, the car won't start.

    I have the factory service manual for the 6th gen Accords, and there is useful information on the immobilizer system. I also have been trying to study this Immobilizer bypass chip to understand how it is fooling the system, but I have no intention to install something like that and permanently disable the factory immobilizer. Here is a thread of people discussing this chip in detail, including a post of something that seems to actually describe what it is actually doing to fool the system, but his description is a little too high level for me to grasp and be able to make use of. Please see post #6 in the thread to see if you can make sense of his description.

    Finally, I bought a bypass designed for remote start systems to see if I can gather any useful information from it. I understand this device somehow reads the RF signal from the transponder key and learns the code, and then somehow can communicate that code to the ECU. The code is stored in something called a EEPROM, a small chip on the immobilizer chip on the ECU.

    My goal is to tap into the immobilizer process with the Raspberry Pi, and somehow disable it when the fingerprint reader attempts to start the car. I can figure out all the nuances of how to achieve this in Python code, but first what I need is to how to achieve this electronically.

    From the devices listed above, I know it is fundamentally possible to:

    A. Completely cut out the immobilizer and fool the system into not throwing a CEL, etc. (immoblizer bypass chip). What circuits are being cut out that disable the immobilizer, but emulate it, and how could I copy this effect?

    B. Learn the transponder key code and be able to send that signal to the ECU at will (bypass module)

    I know all the magic happens in two wires in our car, which the service manual for the bypass module linked above refers to as DATA and SYNCRO. I also see these wires on the Immobilizer Circuit Diagram in the factory service manual.

    Obviously, finding information on this type of thing online is really difficult due to theft concerns, but I don't think any thief would be able to use this information to steal anything due to the high level electrical knowledge required and the difficulty of accessing things like the ECU.

    As a last resort I could just install the bypass module and control it with my Raspberry Pi, but part of the fun is really dissecting these things and understanding on a fundamental level what they are doing. I also feel like a bypass designed for multiple makes and models/years of cars will have redundant circuitry that I could simplify by making a custom bypass for my(our) car.

    Any help greatly appreciated! PM if public immobilizer discussion is discouraged.
     
  2. Jayson

    Jayson Member

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    Sorry the structure of my post is a bit of a mess, but basically what I'm trying to say is I've gathered a lot of information and I'm 99% this is fundamentally possible with the information I have here, but I'm just not quite smart enough to put it all together and figure it out, please help lol
     
  3. Enne

    Enne Well-Known Member

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    The easiest way would be to tape the immobilizer chip up next to the ignition so it's within proximity of the transponder. Then you wouldn't have to disable anything. But I'm sure you'd like a more permanent solution lol.
     

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