Modern day vehicles is full of electronics, different sensors and software. To test that all these different systems works as expected it is suitable to build test beds. These test beds consists of, as far as possible, real components that should be implemented in the vehicles. A vehicle has various temperature sensors. Something that is important totest is how the vehicles systems reacts to different temperatures. This thesis aim is to construct a unit that can simulate a temperature sensor of type PT100. The unit should be able to be controlled via CAN and it should also be able to simulate short cicruit and open load. Digital potentiometers in parallel was used to simulate the temperature sensor. Relays was used to simulate short circuit...