How to Wire a VW Tachometer | It Still Runs The installation of a tachometer in your Volkswagen will not only improve its looks but enable you to track the RPM of the engine, which is very important, especially in racing situations. The installation is pretty straightforward, and one only needs two wires and a mounting place in the passenger compartment for the tachometer. VDO Installation and Troubleshooting Guides Note: These Instructions are for VDO Gauges and Accessories only. Click here for Auto Meter, Classic Instruments, Defi or ISSPRO Instructions. Please note that if you have a problem opening the PDF files just by clicking on the link, please right click your mouse button over the file name and select "Save Target as" to your Desktop.