How can I determine weather my check engine light has been unhooked? The light does not come on when the key is turned to the on position.
Fix the light.
You might want to take it to one the the auto parts stores that will read the codes for free. There may be codes even if the light is not on. I have not played with a reader myself, but if it reads a code, then I would say the system is working and it is just a failure of the lamp. If it does not have any codes or if they can not connect to it, then I would suggest a possible computer failure or tampering.
BTW you really should have it fixed so the lamp works.
The check engine light is always supposed to come on for a few seconds whenever you start the car. The same is true for all of the other warning lights. A car is deliberately made to do this specifically to answer your posted question: Do the lights work properly?
If your check engine light never comes on you can be sure the bulb is either burned out or has been removed. You need only replace the bulb.