ALDL connector

This connector on this vehicle is called and OBD II plug or a Data Link Connector. I will attach a location below but here are a couple guides that will help with this:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://www.2carpros.com/trouble_codes/obd2

See below for the location which is on the driver side under the dash.

Please run through this info and let us know if you have other questions. Thanks