Relay fault detection system and method and vehicle

The invention relates to the field of vehicles, and provides a relay fault detection system and method and a vehicle, and the system comprises a switching device, a current detection device and a controller. The switching device is connected between the branch relay of each battery branch and the branch cathode of each battery branch, and is used for connecting or disconnecting a path between the branch relay and the branch cathode; wherein the branch relay is connected with the branch anode of the battery branch; the current detection device is arranged at the branch cathode and is used for detecting the current of the branch cathode; the current detection devices are in one-to-one correspondence with the branch cathodes; and the controller is respectively connected with the branch relays, the switching device and the current detection device, and is used for performing on-off control on the branch relays and the switching device and performing fault detection on the branch relays according to the current of