Just built up a cable to do scanning of my '93 Z28, using the schematic from here - http://www.home.aone.net.au/~techedge/vehicle/2tran.gif , and I'm using it with a USB-serial converter, as none of my laptops have serial ports. I know the converter works, as it's the same one I use to program my routers. Using both Freescan and Datamaster, I couldn't get squat from the ECM. The USB-Serial converter shows up as COM4 in device manager (XP), but using the TTS ALDL test application, it always said that neither the ALDL cable or PCM could be found (set COM4 in Datamaster). If I set COM3 in Datamaster, it can find the ALDL cable, but still can't find the PCM. I checked off the option for USB-serial converter in Datamaster, as well as chose F-body M6 as the vehicle type. I made sure that I DL'ed the correct version for a '93.

After searching on this forum, and Googling for an hour or so, I found this slightly different schematic on Moates.net - http://www.moates.net/imagery/gmecm/twotran.jpg I seem to remember using something similar to this one when I had my Sonoma, altho that was at least 7 years ago, so my memory could be fuzzy now.

Will either of these cable designs work on a '93? I know everyone will automatically say that I shouldn't waste my time with trying to make my own cable, but I figured it's worth a shot since I already have dozens of the parts needed lying around.