How do I reset my 2007 chevy silverado security system?

First, make sure that You've got a fully charged battery, as You'll need to have the instrument cluster and ECU in working order for this. Turn the key to the ON position, and verify the security light has illuminated. Leave like this for 10 minutes and then turn the key off for 10 seconds. Turn the key on again: If Your engine starts and the light's out, You're good to go. If not, turn to the accessory position, and wait another ten minutes, and then turn the key to off for 10 seconds. Repeat this process for up to 3 times; this should work with any PassKEY system on the 2007 Chevrolet Silverado to reset the alarm.