A body controller may monitor a vehicle bus for diagnostic requests received from a scan device connected to a diagnostic port when a vehicle perimeter alarm of a body controller is armed. The body controller may reset a predetermined lockout timeout responsive to receipt of a session request from the scan device. Upon expiration of the lockout timeout, the body controller may request to establish the session with the body controller from the scan device for a predetermined access timeout. When the session is established, the body controller may allow a user to program entry devices to the body controller and/or download software updates to the body controller.