How do I disconnect my obd11

Question

My obd 2 has been disconnected . I want/ need to reconnect it .
The person I bought the truck from had a 4 ,cylinder and put a 6 cylinder in it but now the check engine light wont come on.

Answer 1

Even if the check engine light will not come on you still will be able to acess any code condition if it occurs.  Change  the light bulb that is in the instrument panel.