Engine codes for '84 T/A

[george dailey]

At 12:55 PM 1/21/96 -0500, you wrote:
>Does anyone have the hexadecimal engine codes for the GM ALDL computers
>as used in '82 through '92?
>
>        Any help would be appreciated.
>
>--- Dan.
*
*
* 
Dan, I also wish to crack the enigma of the GMC CCC serial data protocol.
Here is what I know. Listed below is the "official" pin description from
Chilton repair manuals.  Notice that GM does not distinguish between M and
E.  One source has wrote that M is used in conjunction with E for 'high
speed communication'.  NOT!  My '89 350 TPI set up did not have an E
connection, just an empty slot. This leads me to believe that it is E or M
and not both.  My personal tests indicate that serial data will only be
transmitted when B is grounded. This test was done by  connecting the ALDL
to my PC using Procom terminal software.  All I got was unreadable data .
It appeared in about 3 paragraph chunks that repeated over and over.  I'd be
willing to bet that it's ASCII.  I tried different setting but never got
anything readable.  GM computers can only transmit data ( up to '92 I think)  

What's needed to crack the code is a program that reads a serial data line
and prints it as raw binary data.  Then, any electronic hacker worth his
weight in semiconductors can figure out what's going on.  I'm still assuming
it's ASCII though, I sure as hell don't know for sure.

If one of our suave programmers can write the program,  I would be willing
to connect it to my hardware and share the information that the ECM
regurgitates.   If anybody's interested, the program needs to do the
following in general:

Read pin #3 of a RS232 port
Determine the frequency of the incoming transmission (show us just how
clever you can be)
Collect a few paragraphs (ugh pages?) of data
Print the data to an ASCII data file, line by line in the following format
101000110111001110000111110100101110001010101010001110001001
inform the user of the calculated transmission frequency 

The user then pulls up the ASCII data file in a word processor and tries to
assemble it .  3 endings are possible.

*The code is cracked and we will be immortal in the eyes of all GM car owners.
* The code is cracked and GM marks us for termination.
*We can't make heads or tails of the data and admit defeat.

PS a company called DIACOM makes software that can read the serial data and
print the engine diagnostic information to a IBM PC/AT via RS232 for $300.00
800-888-4146 



>Pin   Function                          
>A       Ground                               
>B       ALDL Diagnostics                            
>C                                                    
>D                                                     
>E       serial data
>F                                             
>G       
>H      not used
>J      not used
>K      not used
>L      not used
>M      serial data
>
>        The connector pinout is arranged in this fashion: [This is true]
>                F E D C B A
>                G H J K L M
>
gmd at tecinfo.com

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