Electronic Killswitch - Hack the ECU?

[Splinter]

I wondering if it'd be possible to remove an essential component of the ECU and build it into a hard plug-in box that has a connector under the dash

The idea is that even someone who was experienced with hotwiring cars would not be able to start the car, since the computer would be non-functional.

[vrg3]

So you could remove that hard plug-in box when you parked the car?

Sure. There are several fairly accessible important pieces on the motherboard. The ignition output transistors come to mind; or maybe the injector driver transistors. Or the fuel pump driver transistor. Lots of transistors.

[Splinter]

Exactly.

That would make it basically impossible to steal.


Im considered tho, that if you removed a piece like that, that it just might fxck the ECU if someone did try and hotwire the car

[vrg3]

Nah; most likely it'd be okay. It might throw a trouble code, depending on how the monitor circuits are wired.

[Splinter]

Hmm

Well, I suppose I'll crack it open and see what's in there that I can relocate.

[vrg3]

What year is your car and what transmission and engine does it have?

[Splinter]

It's Gary's 92 4EAT SS

All should be stock except IIRC, he swapped in the tranny from a regular turbo legacy when the other one gave up the ghost.

[vrg3]

If you pop the cover off the ECU's case (four screws; one in each corner), and look at the top of the circuit board (the side with almost all the components) such that all the markings are right-side-up, there's a 10-pin single-inline-pin chip on the upper right of the case. If you remove the clamp holding it to the side of the case (one more screw), you should see that it's a Hitachi 4AC14. I believe this is the chip that drives the four injectors.

When you mount it remotely, be sure it's mounted to a decent heat sink. Use heat sink compound on its mounting surface too.