Device for protection of electric and electronic components of a vehicle from overvoltages

The apparatus has two contact elements for releasably contacting the two poles of a supply voltage of the vehicle. An electric circuit (5) is connected between the two contact elements. The circuit has a display element for displaying the application of a voltage between the two contact elements. It also has an overvoltage protection element for removing excessive voltages above a threshold value. The circuit further includes a display element (8) for displaying excessive voltages which occur and which are greater than a threshold voltage.