anti-theft chips ?

[Dave Zug]

I'll look for it  - remind me private, I have a full weekend.


----- Original Message -----
From: Programmer <nwester at eidnet.org>
To: <gmecm at diy-efi.org>
Sent: Thursday, October 05, 2000 4:36 PM
Subject: Re: anti-theft chips ?


> Hey--test bench is no problem. Mine just happens to
> have 4 discs and 8 firing pins.
> If you can find that stuff--that'd be fantastic.
> 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 2:35 PM
> Subject: Re: anti-theft chips ?
>
>
> >
> >----- Original Message -----
> >From: Programmer <nwester at eidnet.org>
> >To: <gmecm at diy-efi.org>
> >Sent: Thursday, October 05, 2000 2:02 PM
> >Subject: Re: anti-theft chips ?
> >
> >
> >> 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
> >
> >immediately after the checksum routine place a pointer to a blank
location.
> >checksum is run at key-on, therefore the patch will run immediately after
> >checksum success.
> >
> >> 2. If TPS + 70% or A/C signal high, or .... PRNDL in R_DL once
> >
> >Compare present TPS reference ram location with a $80 or something. If
.GT,
> >then set a ram variable (gotta find an unused bit flag) to true. If not,
> >False.
> >
> >When it comes time to lookup the, say, RPM limit, point to a unused prom
> >location insted of the standard prom location and set it to 1 (25 rpm?)
IF
> >the contents of the flag you set earlier shows improper TPS at key-on.
> >
> >> 3. Then fuel on ??
> >
> >I wouldnt mess with fueling - of coarse on a bench it won't be dangerous.
> >
> >> 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.
> >>
> >
> >I'll try to dig up the code sections. There are 3 areas: JSR after
> checksum,
> >subroutine to compare TPS and set flag, and decision to set the spark
table
> >pointer, whick uses another subroutine.  In order to do this WITHOUT
> >recompiling, the areas in the assembly code that must have JSR's inserted
> >have to REPLACE a certain amount of code, therefore the FIRST thing to do
> in
> >the subroutine is to complete the code that you wiped out for the JSR
> >instruction.
> >
> >Again - ON A TEST BENCH!
> >
> >> 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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