Hello to the forum,
I've just purchased a 92 Sunbird 3.1 SE convertible. The vehicle is a one owner with 52k miles. It runs alright, but it has an issue with the ABS system. I've tried reading the codes, but the Snap-on scanner that I'm using has no communication with the ECM. It has been a really long time since I've worked on a vehicle of this vintage, and to be honest, I've just flat out forgotten how the old OBD1 systems worked. I did verify that the scanner is in working order.
Is there any other way to retrieve the codes from the ABS system? Any ideas of why the scanner can't communicate with the ECM/PCM?

Also, is there any type of fuse, or relay that could be giving trouble, and lastly, is there access to a wiring schematic for this vehicle on this site?

Thanks so much in advance for any ideas, or help, with this situation.

You don't need a scanner to retrieve the codes:

https://www.gmforum.com/specificatio...%2A%2A-278820/

I don't think the paperclip trick is going to work for the ABS system.

i think obd1 scanners require separate power so if it wont communicate its possibly just incapability of the scanner, did you find a list of compatible vehicles that scanner can read

Thanks for the tip, and the link. Unfortunately for me, the ABS codes aren't displayed.

You're correct. Thanks for the input.

The only other OBD1 vehicle I have is a 90 Mazda MX5, and the scanner does work on that vehicle. However, the Mazda has a very basic system, and the scanner does nothing more than what could be found by using a paper clip to jump the necessary terminals needed to make the CEL flash the codes.
An external power supply is needed (power plug, or battery connection) for the Snap-on scanner to function on either of these OBD1 vehicles.
The little information that I can find about the Sunbird wiring system shows the Sunbird to be the only model that has a blk & wt wire going to the diagnostic connector from the ECM, making a total of 4 wires going to the diagnostic connector. As best as I can see, this vehicle only has 3 wires at the diagnostic connection.
I have no idea of what the wire is for because I can't locate an accurate schematic.

Any ideas, or theories on the blk & wt wire?

Thanks again to all for the help.

its a complete guess because i couldnt find a diagram either, but they had different baud rates for different scanners back then maybe it has something to do with that