How the tacho output works
The Nexus drives a tachometer with a pulsed output, switching the wire on and off in time with engine speed. On its own, that output only connects to ground. To give the gauge an actual voltage signal, you need a pull-up resistor between the output and whatever signal voltage your tacho expects. Without it, many gauges will sit at zero. The wiring details are in our tacho wiring guide.
Settings
| Setting | What it does | Our advice |
|---|---|---|
| Pulses Per Cycle | How many pulses are sent per engine cycle | Start with your cylinder count, then adjust until the gauge matches NSP's rpm |
| Tacho Needle Sweep RPM | Sweeps the needle to this rpm at power-up, then returns to normal | Any value you like for the show. Set 0 to turn it off |
If the gauge reads exactly half or double, the pulse count is the culprit. Halve or double it and check again against the rpm shown in NSP at a steady idle and at a higher engine speed.
Some gauges are fussy about the signal they're fed. Haltech makes a Tacho Output Adaptor, and if you're not sure whether your tacho needs it, ask us before you start cutting wires.
