Basic ODB Q's Newbie stuff

[Andrew K. Mattei]

As always, there are exceptions to every rule.

> >The ODBII PCM  is SAE J1850 VPW [ GM]  Starting in 1996 MY and Have Flash
>      EEPROM[s] nonremovable. Have 16 Pin SAE J1962 Diagnostic Connector
>
> >  94-5 MY  ECM's are ODBI with Flash EEproms , also nonremovable
>       Flash equipped PCMs require RW operations via serial link and
require
>      various interface HW and SW variations.

Some late 1995 Blazers are "rumored" to be true OBDII units. Also, the
1994/1995 Corvette 16181333 was a hybrid OBDI and OBDII unit - you
communicate via 8192 or the 10.4 1X mode. You can extract DTC's OBDI style
(12, 51, etc) or OBDII style (P400 etc).

>    94 MY has 12 Pin Diagnostic Connector - 95 MY has 16 Pin Connector
 OBD1 ].
> >  Earlier OBD1 ECMs have UV eracable Eprom - calpack unit which is
socketed.

Sort of. 1994/1995 vettes had OBDII style connectors. 1994 F-cars had OBDI,
1995 F-cars had OBDII style. But 1995 B-cars still had the OBDI style
connector. Darn GM and their tomfoolery!

> >Hope this clears the picture for you.

And hopefully my muddying of the waters will show there's no hard line drawn
with the "standards" that GM used. ;^)

-Andrew

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