Is there a good teardown you know of online of a modern transponder-based system? I did some quick digging and came up empty. The reason I'm curious is that ev

Is there a good teardown you know of online of a modern transponder-based system? I did some quick digging and came up empty. The reason I'm curious is that every time I've looked inside a consumer-grade electronic lock, all of the "security" is in the part that's physically accessible to the user, and then there's just a pair of wires that goes to a relay or an I/O pin (+ground) in the main control system. i.e. it's generally trivial to just figure out what needs to be done with those two wires, and forget looking at the innards of the security mechanism entirely. Caveat: I have only examined a handful of such devices, not conducted an extensive survey. In this case, what I'm imagining is that since the car half of the transponder pair needs to be near the ignition switch[1], there's a decent chance that it's a complete module with maybe 3-4 pins connecting it to the rest of the car - power, ground, and either "key detected" pin or relay power. Obviously it would be safer to have the module simply route signals between the ECU and the key, so that bypassing the lockout would require tampering with the ECU, but my limited experience described above makes me think there's a non-zero probability that at least some manufacturers went with the self-contained module approach. [1] In at least some configurations. For cars where the transponder works anywhere near the vehicle, this would not be the case. Edit: replaced asterisk with footnote indicator to avoid italics in the wrong place.