How to Wire a VW Tachometer

Decide where the tachometer will be mounted. This is an important step, because you need to know how much wire to use and where to route it. Some people mount them to the steering column with hose clamps, some mount them in external cases on the dash and some actually make room in the dash for the new tachometer. It is recommended to mount it before wiring it for precision. Some tachometers have bucket switches in the back of the unit to adjust for 4-, 6-, or 8-cylinder engines. Check the owner's manual to ensure the correct settings.

Hook the red wire into a power source. Decide where you wish the tachometer to get its power from, and splice the wire into it. It will be necessary to wire the tachometer into a source that only receives power when the ignition is on or it will be a constant draw on the battery. Carefully route the wire to the source, as well. This wire has electricity going through it, and if it gets damaged or grounds out, it could ruin the tachometer and start a car fire.

Connect the black wire to the negative (-) side of the coil. Once again, it is very important to route the wire in such a way that it does not become damaged. When running any electrical wire through the firewall to the engine compartment, always use a rubber grommet to eliminate the chances of chafing. To hook it onto the negative side of the coil, it is necessary to attach a blue circular wire connector on the end of the wire. Then remove the nut that is on the coil, place the ringed wire tip over the shaft, and replace the nut snugly. The tachometer will now show what RPM the engine is at once it is started.