ALDL is the old rectangular 12-pin plug. If you jump two of the pins, the dashboard check engine light flashes out the diagnostic codes. My car has a
16-pin trapezoidal OBDII plug, but it is a 1994 with ALDL wires stuck in the OBDII plug. The 1994 car is not OBDII compliant, so the OBDII code reader doesn't work on it. I just have to figure out which two pins to jump so the dashboard check engine light flashes the diagnostic codes.I'm not sure of this, so I ordered a wire with USB on one end and OBDII on the other. This is called,
ALDL (GM OBD1) Cable with 16 pin Connector, USB
the catch is I have to download the freeware to use it. When I get the wire I'm testing it with my multimeter to get the pinouts on what wire goes where. Then I'm puting the configuration on my web site so anyone can make one for ten bucks.
I'm not going to fry my computer over some of these nitwits making a profit off of consumer ignorance, but it looks like that's where I'm headed. For instance, you can't make a direct serial connection between automobile 12 volt line voltage, or woops, there goes your serial port, if not your whole PC. The same can happen with a USB port. Why do you need another computer to read one computer? That's what the ECU car computer is for. Nevertheless, people like to sell you junk.
By the time you buy everything to fix it yourself, you've spent enough on gizmos you'd been further ahead to take it to a dealer shark.