Can anyone identify this plug?

Hi there,

I bought a '98 Tahoe and there is this plug under the dashboard. The pre-owner doesn' t know its function. Can anyone help?

It is likely aftermarket and the possibilities are:

Trailer brake connection;

Security/remote start connection;

Plow control;

Radio equipment;

Temporal flux capacitor.

DOD disable?

1998 did not have variable displacement/cylinder deactivation. That's probably why it is still running.