If your Cadillac hood won't stay up on it's own, the issue in most cases has evolved from weak hood supports.
You have just purchased an OBD-II scanner to check Cadillac fault codes, but are having a hard time locating the place to plug it in.
The diagnostic port, also known as OBD-II or OBD2 port, on Cadillac vehicles is located under the dashboard on the driver's side. Look under the dashboard right above the brake pedal.
Most Cadillac including ATS, Escalade, CTS, SRX, STS, XTS, CT6, XT5 have the On-board Diagnostic (OBD) port under the dashboard on the driver's side.
The diagnosis port will allow you to read and clear fault codes from the Engine Control Unit. If you have an All System Scanner for Cadillac, you will be able to read and clear codes from any module, including transmission, airbag SRS, transmission, climate control, ABS, traction control and more.
A basic OBD-II scanner will only access trouble codes related to the engine. It will not show any other fault codes even if warning lights are on.