Abstract: A diagnostic device for checking a control signal line between a control device of a motor vehicle and a motor-vehicle-side charging connection for a battery of the motor vehicle, includes a first resistor disposed at the charging connection and connecting the control signal line to ground, a second resistor connected in parallel with first resistor to form a parallel circuit, an evaluation device associated with the control device and comprising a current source and/or a voltage source for supplying a corresponding current or voltage outside a charging operation, and a diode connected in series with the first and second resistors and blocking a current flow from ground to the control signal line. The evaluation device is configured to measure, by using the first and second resistor, a current indicating a control signal line defect or a voltage indicating a control signal line defect.

Abstract: A diagnostic device for checking a control signal line between a control device of a motor vehicle and a motor-vehicle-side charging connection for a battery of the motor vehicle, includes a first resistor disposed at the charging connection and connecting the control signal line to ground, a second resistor connected in parallel with first resistor to form a parallel circuit, an evaluation device associated with the control device and comprising a current source and/or a voltage source for supplying a corresponding current or voltage outside a charging operation, and a diode connected in series with the first and second resistors and blocking a current flow from ground to the control signal line. The evaluation device is configured to measure, by using the first and second resistor, a current indicating a control signal line defect or a voltage indicating a control signal line defect.