anti-theft chips ?

[Dave Zug.]

Under cranking the line from the FP relay is overridden by the oil pressure
switch and the car will fire right up (crank for 10-15 seconds). Chip
security is defeatable by (as said) tow truck or limp home.

disconnect speedo = 0 mph.  again, pros will just tow it... amateurs will
bash it up in frustration if they can't steal it.

The address lines thingy is all over the archives.. many implementations.
lookup thumbwheel (is that copyrighted?).. read the areas related to hot
switching if you really want to do a nice job... I beleive the archives
still leaves a little assumption that you know the basics.



----- Original Message -----
From: <timsiford at hushmail.com>
To: <gmecm at diy-efi.org>
Sent: Thursday, October 05, 2000 12:39 PM
Subject: Re: anti-theft chips ?


> Here's a quick idea....
>
> We've been discussing programming two images onto a double size chip and
> then using a SPDT switch to control which image we are using on
thirdgen.org
> (kudos to Tim Burgess!)....
> http://www.thirdgen.org/messageforum3/Forum10/HTML/000072.html
>
> Couldn't you just program one image to have a maximum speed of 0mph and
> the other image to function normally?  Seems that easy in theory.
>
> Why even worry about all that anyhow?  You could just wire up a fuel pump
> kill switch using the FP ground.
>
> Tim
>
>
> At Thu, 5 Oct 2000 12:02:39 -0600, "Programmer" <nwester at eidnet.org>
wrote:
>
> >
> >I'd think that any type of anti-theft system may be a hodge-podge in
> >an
> >emergency...
> >I'm not much of a software compiler guy, Dave. Been years since I wrote
> >basic <G>...if I wanted to do this in
> >a 7747 bin--how'd I do it ?? I know somebody wrote code to
> >put a speed limiter in a 7747 bin--and it works great. If it's shown
> >to me once...I'm a quick learner. I've seen this before somewhere in
> >my
> >internet travels, but can't remember where. Somebody mentioned a
> >"secret start" sequence -- maybe it was at the GN site, I dunno. I'm
> >not
> >sure
> >if this would work but, how'd you write:
> >1. If Key on
> >2. If TPS + 70% or A/C signal high, or .... PRNDL in R_DL once
> >3. Then fuel on ??
> >Will the PCM see this as a one time event at start up--it should I guess?
> >If you don't have time help--no problem...I'll try to figure something
> >out.
> >
> >Lyndon.
> >
> >-----Original Message-----
> >From: Dave Zug. <dzug at delanet.com>
> >To: gmecm at diy-efi.org <gmecm at diy-efi.org>
> >Date: October 5, 2000 7:58 AM
> >Subject: Re: anti-theft chips ?
> >
> >
> >>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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> >>>
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