A cooling system for a vehicle includes a first cooling circuit coupled to the vehicle engine for cooling the latter and a pump arranged in the first cooling circuit for pumping a coolant to the engine. The system further includes a second cooling circuit for cooling at least one other component in the vehicle, and an arrangement for coupling the second cooling circuit into the first cooling circuit in order to also supply the second cooling circuit with coolant from the pump. The cooling system further includes a line coupled from the first cooling circuit to the second cooling circuit bypassing the coupling means so that the second cooling circuit is supplied with coolant from the pump via the bypass line even when the coupling means is set to the disconnected position.