A control module arrangement for a compressed air maintenance unit constructed like a battery and a compressed air maintenance unit, which has several maintenance modules in a row one after the other, wherein the control module arrangement has a bus interface for communicating with the maintenance modules via an internal bus of the maintenance unit. The control module arrangement has a diagnostic device for communicating with an input/output device of the maintenance unit, wherein the input/output device has a connector for connecting at least one diagnostic sensor separate from the maintenance unit and/or at least one pneumatic compressed air influencing actuator separate from the maintenance unit, wherein the control module arrangement can control the one or more compressed air influencing actuators via the input/output device and/or can receive diagnostic messages from the one or more separate diagnostic sensors.