I am searching for my ALDL on my 1989 sword custom 3.8 L. I finally found this 12 point connector....however to me it looks almost like a part of the HVAC system since it'* so close to the vacuum climate control unit....?


This shot only shows 4 electrical connectors active....



I didn't get any time to run any electrical check w/ A-B short or multimeter because the wife needed to run....

The Haynes manual doesn't show any wire location or description w/the ALDL....& the connector didn't appear to have any description or marking showing A thru M.....

Haynes also mentions that some some vehicles (Buick manual) don't have a terminal B present in the connector....(reads: requires a scan tool or go to the dealer)

Anyone know what the 4 electrical wires connect to from the 12 point terminal ALDL....? It might be A, B, M & F...? Terminal twisted to see the bottom view...


Side view...normal vertical position view...not attached...


Your thoughts & experiences will be greatly appreciated...

Yes, that is your ALDL connector. You only need a short jumper wire to jump pins A and B together. Turn ignition on,(but don't start the engine) and count the flashes. The first code is always going to be 12. This code indicates the diagnostic system is functioning properly.

To determine which way is up, look at the stub on top of the connector in the picture, not orient your connector so it matches this one and you will know where your A and B pins are.






To clear any codes, disconnect battery for a few mins, reconnect and go for short test drive to see if check engine light comes back on. This should only apply if you have recently made repairs.

Remember, to read the flashes, there is a short pause between each number and a longer pause between each stored code.
example: code 12---flash,pause, flash, flash-pause pause to indicate next number.
code 25---flash,flash, pause, flash, flash, flash, flash,flash. pause pause for next number. etc etc. Hope this helps.