[NTLUG:Discuss] new to list, have a question

[Steve Baker]

Rev. wRy wrote:
> On Sat, 2003-12-06 at 08:24, Clay Ramsey wrote:
> 
>>I hope that some of you are gearheads as well!  ;)

Me!  Me!  I'm a gearhead *and* a geek!

>>DO any of you know of any software (Lin based of course) that I can use
>>to re-program the chip in my truck, as well as talk to the computer to
>>hear what may be wrong with sensors etc etc???  I already have a RH 7.3
>>laptop, so all I need is the software (and connector).

Hearing what's wrong with the sensors is possible.  Many of the codes
are standardized (by California State law) - some others can be found
on gearhead web sites - yet others are secret, known only to the manufactureres.

So, you can read the codes - but you may not be able to find out what
they all mean.

You can also (typically) clear out codes for problems you may have
fixed yourself.

My MINI Cooper'S has an unholy nasty feature - if you don't tighten up
your gas cap, it triggers a warning light that you can only clear
by taking it to the dealership.  So using something like freediag
to zero it out is a really useful thing!

However, reprogramming the computer is next to impossible...read on...

> Check sourceforge.  Several projects popped up simply searching on
> 'vehicle' including:
> 
> http://sourceforge.net/projects/freediag/
> 
> "Freediag is a suite of vehicle diagnostic protocols and an OBD II
> (mostly) compliant Scan Tool, currently for Linux platforms."

Those tools allow you to probe diagnostic codes and reset faults and
such - but they emphatically do not allow you to reprogram your cars
software.

I'm a MINI Cooper maniac (we MINI owners hang out at www.metroplexMINI.org).

I've worked long and hard to figure out what it takes to reprogram the
ECU chip in a MINI - and it's NOT easy.

I don't know in detail about your truck - but most modern vehicles
have careful and secret protocols to prevent 'unauthorised' reprogramming
of the Engine Management Unit (ECU).   The companies that offer 'chipped'
ECU's spend most of their R&D money figuring out how to crack those
protocols and they DON'T reveal what they know *EVER*!

As I understand it, there are 256 numerical 'algorithms' (probably math
formulae of some kind) that a manufacturer can choose between - and
each car has a 16 bit 'random' code built into it's ECU ROM.

When the 'programmer' (typically a laptop with a OBD-II serial port
adapter) tries to download new software to the car, the following
thing happens:

1) The car sends it's 16 bit unique ID.
2) The programmer knows which of the 256 algorithms this car
    uses.
3) It feeds the 16 bit number from the car into the appropriate
    formula - and computes a 16 bit result.
4) This new 16 bit number is sent to the car.
5) In the case of the MINI Cooper, if the number doesn't match the
    number the car expects back, the ECU shuts down and refuses to
    do anything (even unlock the car doors!) for three hours.  I'm
    told most cars aren't that extreme - but suffice to say repeated
    trying of all 65536 response codes isn't going to work.

This is a hard nut to crack!

The way the 'chipping' companies do it is to beg/borrow/steal a legal
programmer (eg by bribing an employee at a car dealership) - and they
program a PC to behave like a car's ECU computer would.  Then, they
can carefully feed the 'legal' programmer all 65536 possible codes
for one of the algorithms - and record all of the bazillion results the
programmer returns.

However the car manufacturers typically limit the rate at which these
programmer machines will download code.  That can make doing a full
search of the entire number space take an insanely long time - so
it's safe to say that nobody has cracked all 256 algorithms - which
is why chipping companies typically only support a few car types.

Welcome to the wonderful world of DRM.

There is an OpenSource package to completely replace the entire
engine management computer with a complete new (Open) hardware
design - and consequently allow you to put any software you like
in the car.

That would take a LOT of nerve - bad ECU software can do LOTS of
damage - and possibly be life-threatening!

I don't have the URL, but it shouldn't be hard to find.

    :-(

---------------------------- Steve Baker -------------------------
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HomePage : http://www.sjbaker.org
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