What this page sets up
The Aux Limiter only acts when its switch says so. The Wiring page is where you tell the ECU which input that switch is on and how to read it. Assign it under AUX RPM Limiter Switch Input. Any free SPI or AVI will do.
First, work out what your switch actually does to the wire when you flip it. That answer drives every setting below:
- It grounds the input (most common, and our preference because it's simple and safe).
- It supplies voltage to the input, for example 12V from a switched feed.
Setting it up on an SPI
| Setting | What it does | Our advice |
|---|---|---|
| Edge Select | Which signal change means "switch on" | Falling for a switch that grounds the input. Rising for one that feeds it voltage |
| Sensor Type | How the input interprets the signal | Hall Effect, which is the correct choice for any switch input |
| Pullup | Holds the input at a voltage while the switch is open | Enable it for a ground-switching setup, or the input floats |
Setting it up on an AVI
An AVI measures voltage, so instead of an edge you give it two thresholds: Switch On Voltage and Switch Off Voltage. The ECU treats the switch as on once the voltage crosses the on value, and doesn't treat it as off again until it crosses back past the off value. The space between the two is your protection against a noisy signal making the limiter chatter.
Here's how that plays out for a ground-switching setup, where the input idles near 5V and drops to 0V when switched:
- Log the input voltage with the switch off, then on. You should see roughly 5V and 0V.
- Put the on threshold near the bottom, around 0.5V to 1.0V.
- Put the off threshold near the top, around 4.0V to 4.5V.
For a switch that raises the input, reverse the logic. If the input rests at about 2.5V and jumps to 12V when on, an on threshold of about 4.5V and an off threshold of about 3.0V gives clean switching.
If on and off are set close together, a sagging battery or a vibrating connector can bounce the input across both thresholds. On a rev limiter, that means the limit flicking in and out. Keep the thresholds well apart.
After the wiring
Once the switch reads correctly in NSP, set the limit itself with Aux RPM Limit, choose how hard it cuts with Aux Cut Percentage, and use the Aux Adder if you need it. A dual switch panel kit makes a clean dash-mounted switch.
