If you have aftermarket LED BRAKE LIGHTS:

LED Brake lights are known to retain voltage on the cold side of the Brake switch even when the vehicle is turned Off and the Brake is not being depressed. This becomes a problem in that the iKEY system interprets voltage on the cold Brake line to mean the Brake pedal is being pressed and triggering the alarm since it does not see a valid fob in range, In this case it is necessary to add a diode in line (band facing the switch) to prevent back feeding voltage.