The Volkswagen/Audi special tool VW 1301 is a simple resistance substitution box used to check instrument cluster gauge operation. Some newer versions of this tool are identified as VAG 1301 or VAS 1301, but all serve the same function which is to replace the gauge sending unit with a known resistance value. Once this known value is in place, the gauge in question can be observed for correct calibration. This information can then be used to determine if the fault lies with the gauge, the sending unit or the wiring connections.
The resistance dialed into the VW1301 is not input as Ohms, but rather as reference units. These reference units are easily converted into Ohms in the accompanying table for use with fixed resistors or commercial resistance substitution boxes.
Due to the relatively small amounts of power used by the instrument cluster gauges and low power handling capability of the VW 1301, it should only be used for instrument cluster gage testing.