PCM connectors

[Andrew Mattei]

"Jason R. Haines" wrote:
> The 1994 - 1995 LT1 Corvette uses the flash PCM part number 16181333. The
> 1994-1995 LT1 Camaro, Firebird and Impala use the flash PCM part number
> 16188051. I am not sure what the difference is. For 1996, they all use part
> number 16214399.

The 16181333 (Y-body PCM) has a smidgen of OBDII in there, and has a
couple extra chips to help implement it. The 16188051 (F/B/D) PCM does
not have these chips, nor does it support these OBDII style
communications. However, you CAN reprogram a 16181333 with the code from
a 16188051 and have it work the same as an F/B/D PCM.

The 'vette used these OBDII style communications because of the sheer
number of computers it has on board - ABS/TCS, Airbag, HVAC, Central
Command Module (CCM), active suspension, etc... There's a lot of stuff
talking on board a later model 'vette.

The CCM controls communications on the OBD bus on the 'vette, so I don't
know if a PCM being "standalone" will start talking without the proper
commands (unlike the F-body calibration on the 8051 which will blabber
all day long). I have observed that if you remove power from the CCM but
not the PCM, the PCM shuts up.

If you look at a Helms manual for a 1994 vette, you'll see a listing of
standard OBDI style trouble codes in there, as well as OBDII trouble
codes. It's a hybrid.

Later,

Andrew
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