Playing with the ECM

[Lawrence E. Piekarski]

>
>>If someone like me, or you, or Hypertech, tries to gain access and change level
>>three type of information in the new '97 VCM, and does not have the correct
>>access code the FIRST TIME, the VCM will lock itself down into a
>>non-functional unit that cannot be restarted except by engineers at Delco!!
>>
>Yes, I personally think OBDII is going to throw the aftermarket a really big 
>curve.  Hacking into the box and reprogramming it is going to be harder 
>still.  Removing the EEPROM and recalibrating it in such a way that no SES 
>lights will be set will be even harder still.  I haven't heard anything 
>about VCM's rendering themselvs useless with bad ClassII messages.  I think 
>this one is wild speculation.  Any of you other Delco guys (or gals) care to 
>comment?

I have heard that also. I don't think a bad Class II message would cause it to
lock up, but there were two different modes that would cause the device to 
set a code that would disable fuel and could not be cleared by the dealer.
On was if it failed ROM checksum. I can't remember the other. I thought that
requirement was one of the more advanced OBDII requirements. I haven't worked 
with the stuff in over a year, so maybe it's changed. It seemed there was
a lot of waffling on the issue a year ago, so there probably still is.

I guess CARB was upset that people just drove around with a bad sensor and the
check engine light on. They want to disable fuel under certain conditions to
FORCE your to take your car in. In 1984, Big Brother was watching, in 1997
he drives your car.
-- 
(* Larry Piekarski, Lead Software Engineer *)
(*      Luxury Car HVAC Display Heads      *)
(*      lepiekar at mail.delcoelect.com       *)
(*      Delco Electronics, Kokomo, IN      *)