anti-theft chips ?

[Dave Zug.]

in '97 or so, I patched in code (manually - no compiler) after the checksum
to check TPS and compare it with 50%. checksum occurs at key-on and not
otherwise (from what I could find - no other calls to the start of the code)
based on the comparison I would select 1 of 2 spark tables when it came time
to do the 3d lookup. I suppose if you either put the execution into an
endless loop if TPS is not above 50% when the key is turned on. Interrupts
may override this though. I made a lengthy post regarding exactly what I did
maybe a year ago. another consideration is liability of coarse.  If the car
must be started in a panic, or BORROWED in an emergency it could gum things
up. If an accident occurs it will take high paid experts to testify that
there is no way your patch was responsible.

DISCLAIMER - DO THIS ONLY ON A TEST BENCH, for fun  ;-)

EFI performance made a security version for their GN chips that required a
sequence of activities, something like key, neutral, park, TPS, crank.



----- Original Message -----
From: Programmer <nwester at eidnet.org>
To: <gmecm at diy-efi.org>
Sent: Thursday, October 05, 2000 2:35 AM
Subject: anti-theft chips ?


> Anyone ever figure how to write a secret start sequence so
> one wouldn't have to shell out big bucks for an anti-theft
> system that is so easily bypassed ? My secretarys' husband
> had their 89 C1500 SWB stolen right from in front of their house.
> They heard the truck start up and drive away--thought it was a
> neighbor <g>. That was last week--got the truck back today,
> luckily--the idiot that stole it was caught driving drunk...otherwise
> they probably wouldn't have had any action on it at all...
> Lyndon.
>
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