Flashing a 8051

[daklein at netzero.net]

At 12:31 AM 7/10/01 -0400, you wrote:
>Assuming you're using the max232 converter, the simpler two transistor one 
>worked only sometimes (not on the old beat caprice, fine on the younger camaro)
>
>I also had trouble when wiring too long a permanent cable between aldl & 
>converter

Actually, I remember now what seemed to be the root of my trouble when I 
thought maybe the cable was too long, (and may have been part of the 
trouble with the two trans converter in the caprice).  Sorry for the saga.....

I think the ground used to connect the interface matters.  At least in the 
95 camaro, which has the OBDII connector, there are two separate ground 
wires in the ALDL connector.  Looking thru the manual, pin 4 is the I/P gnd 
ultimately going to the driver side kickpanel body, pin 5 is the real PCM 
ground.

I probably would never had any trouble if had just gotten the interface & 
cable & aldl connector from Andrew to start with.  But no, more satisfying 
to make it myself

Originally I made a two transistor interface wired permanently into the 
camaro, and had no real problems with it, programmed a half dozen times, 
and freescan would maintain comm
for 30 min or longer rides.  Don't remember which gnd I used.

During winter, got a caprice wagon & tried the same thing, making another 2 
trans converter, but would not work.  the wagon is a 94 & has the OBDI ALDL 
connector.  I don't have a manual for the caprice, does anyone know if both 
gnd circuits are there like the camaro?  I've been using the ground at pin 
A, upper right looking at connector for both the .  After goofing the PCM, 
I got the max232 converter, but skipped the OBDII connector, and it works 
great in the wagon

Spring time, get the camaro out, don't trust the two trans converter after 
recent lessons in PCM shipping to Texas.  when I wire in the cable between 
converter & car, not knowing, I pick pin 4 to use for gnd.  Hardly works at 
all... WTF...?  cable is really plenty long, longer than before, maybe 
that's why.  even after shortening cable to ~3 ft, still no good.  happened 
to try pin 5 gnd, and seems to works fine.  Looked in manual to see where 
exactly the gnd wires go, and it makes sense that it works.  Only thing is 
that freescan or other scanners will drop out after a few minutes usually.

Question, Andrew or anyone else,
         the converter has a separate 'power' gnd & ALDL gnd.  probably the 
ALDL gnd needs to be connected to the PCM gnd.  what about the power 
gnd?  should it be also hooked to the PCM gnd (tying the two gnds 
together), or should it go to the I/P-body gnd.

Thanks,
         Dale




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