A condition monitoring system using an inter-vehicle network consisting of wireless communication devices has been proposed to monitor railway vehicles’ condition from the cab while the vehicles are in motion. In order to reduce the power consumption of these wireless communication devices, it is possible to put the devices to sleep while the vehicles are detained. It is necessary to synchronize the clocks of the wireless devices to reconfigure the inter-vehicle network in a short period of time after the sleep. We propose time synchronization methods that periodically exchange broadcast messages with neighboring devices.