The first thing to do is to know which type of tachometer. If it is a pointer type tachometer of ordinary instrument, there are usually two wiring methods, one of which is to connect the ignition module. For example, the EXT terminal of the Toyota car on the ignition module is used to connect the tachometer in the instrument. Is the frequency signal. However, such connection methods are currently rare, mainly used in the old distributor ignition mode. The other signal comes from the speed sensor, which is the crank angle sensor, usually installed in front of the crankshaft of the engine (behind the crankshaft pulley); in the middle of the crankshaft, deep inside the crankcase, with the weight on the crankshaft as the signal generator; the rear of the crankshaft It is usually installed next to the big flywheel and uses the flywheel teeth as a signal generator.

If it is a tachometer controlled by the instrument control module, the typical characteristic of such a meter is the liquid crystal display. Although the tachometer signal is also derived from the speed sensor, the signal is obtained by the instrument control module through the CAN bus through the engine control module.