A measurement module comprising a measurement circuit for obtaining a measurement value of a trailer lamp drive signal during at least part of a driven state and a wireless interface for transmitting a signal indicative of the measurement value of at least one electrical parameter of the trailer lamp drive signal to a user device to allow the user device to inform a user of the measurement value of the at least one electrical parameter or an indicator derived thereof, - the measurement module being connectable to an output terminal of an interface module to receive the trailer lamp drive signal from the selectively driven output terminal, - the interface module being comprised an interface device for connecting an auxiliary lighting system to a vehicle lighting system of a vehicle and driving the auxiliary lighting system from the vehicle lighting system, the interface module comprising: - the output power terminal for electrically connecting to the auxiliary lighting system via a tow bar cable, - a control terminal for electrically connecting to the vehicle lighting system for receiving a control signal corresponding to an operation of a lamp of the vehicle lighting system, - a semiconductor driving device electrically connected to the control terminal for selectively driving the output power terminal in dependence on the control signal for operating a lamp of the auxiliary lighting system corresponding to the lamp of the vehicle lighting system, the control signal being in a drive state selected from at least a driven state and a non-driven state, - a measurement circuit for obtaining a measurement value of at least one electrical parameter indicative of a performance of the lamp of the auxiliary lighting system during at least part of the driven state, - a wireless interface (361, 362) for communication with a remote user device external from the vehicle and the auxiliary lighting system, and - a processor arranged for sending, via the wireless interface, a signal indicative of the measurement value of the at least one electrical parameter to the user device to allow the user device to inform a user of the measurement value of the at least one electrical parameter or an indicator derived thereof. - the measurement module being connectable to an output terminal of an interface module to receive the trailer lamp drive signal from the selectively driven output terminal, - the interface module being comprised an interface device for connecting an auxiliary lighting system to a vehicle lighting system of a vehicle and driving the auxiliary lighting system from the vehicle lighting system, the interface module comprising: - the output power terminal for electrically connecting to the auxiliary lighting system via a tow bar cable, - a control terminal for electrically connecting to the vehicle lighting system for receiving a control signal corresponding to an operation of a lamp of the vehicle lighting system, - a semiconductor driving device electrically connected to the control terminal for selectively driving the output power terminal in dependence on the control signal for operating a lamp of the auxiliary lighting system corresponding to the lamp of the vehicle lighting system, the control signal being in a drive state selected from at least a driven state and a non-driven state, - a measurement circuit for obtaining a measurement value of at least one electrical parameter indicative of a performance of the lamp of the auxiliary lighting system during at least part of the driven state, - a wireless interface (361, 362) for communication with a remote user device external from the vehicle and the auxiliary lighting system, and - a processor arranged for sending, via the wireless interface, a signal indicative of the measurement value of the at least one electrical parameter to the user device to allow the user device to inform a user of the measurement value of the at least one electrical parameter or an indicator derived thereof. - the output power terminal for electrically connecting to the auxiliary lighting system via a tow bar cable, - a control terminal for electrically connecting to the vehicle lighting system for receiving a control signal corresponding to an operation of a lamp of the vehicle lighting system, - a semiconductor driving device electrically connected to the control terminal for selectively driving the output power terminal in dependence on the control signal for operating a lamp of the auxiliary lighting system corresponding to the lamp of the vehicle lighting system, the control signal being in a drive state selected from at least a driven state and a non-driven state, - a measurement circuit for obtaining a measurement value of at least one electrical parameter indicative of a performance of the lamp of the auxiliary lighting system during at least part of the driven state, - a wireless interface (361, 362) for communication with a remote user device external from the vehicle and the auxiliary lighting system, and - a processor arranged for sending, via the wireless interface, a signal indicative of the measurement value of the at least one electrical parameter to the user device to allow the user device to inform a user of the measurement value of the at least one electrical parameter or an indicator derived thereof.