Cant reprogram my immobillizer cause my security light shuts off after five seconds chevy equinox 2012

The equinox of this year are a bit odd, is it a used ECM or new one?

For the most part you are not be able to reprogram used ecms of this type unfortunately because the way the VIN and security data is stored. Basically, you can not rewrite it. Even if you had it flashed you will see it still has the ecm's original vin. You will need to buy a new one, flash it with SPS and then do the procedure to learn the keys.

If it is a new ecm are you manually trying to program the keys or using a diag tool?