12 pin GM ALDL

[Six_Shooter]

Just get something like this and you are good to go, make sure it uses ftdi chip.

https://www.ebay.com/itm/381374421597?_ul=BO

You still need additional hardware to make that work. There's a MAX232 IC and supporting hardware needed to make that work with the GM ALDL databus. I have one that I made out of a similar USB to TTL adapter, it works very well, but needs to be made more robust and installed in an enclosure...