DIYEFI FAQ

[Robert J. Korn]

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George M. Dailey wrote:
>  I'v been thinking about writing a FAQ
> on the GM ALDL thing, but it will be a while before I do.  I've been
> collecting the posts on ALDL for about a year. I'll simply put them all

I posted this message last month but never saw it come back.
This is a rs232 to ttl level converter that should work for the 8192
baud ecm's.

I used it a few times on non auto related projects. I haven't tried it
yet
 on a car. You can delete the inverter if if you want a one way
interface.

The serial data would seem to be two way. The data line also goes to 
the ABS brake controller. I saw a thread about the possible
interaction between the brakes and the ecm. According to the wiring
in my car its possible........

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              +-------------+  +             
  +-----------|1          16|---+---o +5V (VCC)
 +|          +|             |  ===
 === +5V o-||-|2  MAX232  15|---+---o GND (card & RS-232)
  |           |             |
  +-----------|3          14|
           +  |             |        o +5V                     
     +---||---|4          13|        |
     |        |             |        \          
     +--------|5          12|        / 10K
          +   |             |        \
     GND o-||-|6          11|        /
              |             |        |
     RxD o----|7  ---<--- 10|--------+----------+----o ALDL I/O
              |             |              |\   |
     TxD o----|8  --->---  9|--------------| |--+
              +-------------+             1|/ 2
                                          74LS07
    
       (also connect to 74LS07, pin 7=GND, pin 14=VCC)



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