In my search for raspberry pi info, i found some posts that spell out an alternate, easier cable to pull aldl data. I did a search for A max232 ttl level usb interface.
Once received, join the tx and rx breakout pins together, that goes to data aldl, and the ground pin goes to the aldl ground. Once the driver is installed in your computer, it will be chatting up your ecm in no time! WAY EASIER than building a cable!