A vehicle test system including a plurality of apparatuses mutually communicable via a network. A control apparatus included in the apparatuses controls two or more objects in the vehicle by using respective control modules each having fault detecting module used to detect fault in the object being controlled. A test apparatus connected to the control apparatus commands any one of the control module included in the control apparatus in order to read out fault information in the objects. The control apparatus generates, in response to the test apparatus, a response command indicative of the fault information detected by the fault detecting module and transmits the response command to the test apparatus via the network. The response commands includes both fault information corresponding to the control module to which the test apparatus commands and fault information corresponding to the other control module.