Why wire a clutch switch
A clutch switch tells the ECU whether the pedal is pressed. On an Elite, that single signal feeds several features:
- Launch control: a common way to arm a launch limiter is clutch in plus a speed or switch condition. Release the clutch and the car launches.
- Gear detection: when paired with a gear switch, the clutch state helps the ECU work out which gear you're in.
- Logging and tuning: seeing the clutch in a log makes shift points, launches and driveline shock far easier to read.
Many cars already have a clutch switch for cruise control or starter lockout. You can often use that switch rather than fitting a new one.
Picking an input
In the function's Wiring tab, choose the Clutch Switch Input. Either an SPI (Synchronised Pulsed Input) or an AVI (Analogue Voltage Input) will work. The settings you'll see depend on which you pick.
On an SPI
| Setting | What it does | How to set it |
|---|---|---|
| Edge Select | Which voltage change means "clutch pressed" | Falling if pressing the pedal connects the input to ground. Rising if pressing it supplies voltage to the input |
| Sensor Type | How the input reads the signal | Hall Effect for any switch |
| Pullup | Holds the input at a known voltage while the switch is open | Enable it when the switch only grounds the input, so there's a voltage to see when it's released |
The most common wiring is a switch that grounds the input: pull-up on, falling edge. It's simple and needs only one wire to the ECU.
On an AVI
An AVI reads the actual voltage, so you define two thresholds: Switch On Voltage and Switch Off Voltage. The ECU considers the switch on once the signal passes the first, and off once it passes back across the second.
The gap between the two is deliberate. Real wiring has noise, a little ground offset and voltage that moves with the charging system. With a single trip point, the signal can flicker across it and the ECU sees the clutch turning on and off rapidly. Two separate thresholds give you a dead band in between, where nothing changes.
Log the real voltage with the pedal up and down first. Then put each threshold well inside the gap between those readings, never right at the edge.
Worked examples
A switch that pulls the input to ground
Released, the input sits at 5 V. Pressed, it drops to 0 V. A tight setting that still leaves room for noise is On at 0.5 V and Off at 4.5 V: the clutch counts as pressed once the signal falls under 0.5 V, and released once it climbs back over 4.5 V. If your logs show a noisier signal, widen the margins, for example On at 1.0 V and Off at 4.0 V.
A switch that supplies 12 V when pressed
Some factory switches feed battery voltage when the pedal goes down, and float around 2.5 V when released. Here the logic flips: the on threshold sits above the off threshold. Setting On at 4.5 V and Off at 3.0 V means the ECU sees the clutch pressed once the signal rises past 4.5 V, and released when it drops under 3.0 V.
Before using battery voltage on any input, confirm that input is rated for it on your ECU. If you're unsure, check the pinout for your model or ask us.
Troubleshooting
| Symptom | Usually |
|---|---|
| Clutch always reads pressed, or never | Edge set the wrong way, or the pull-up is off on a ground-switching switch |
| Clutch status flickers in the log | AVI thresholds too close together, or a poor ground at the switch |
| Launch control won't arm | Clutch input not reading pressed. Check it live in ESP before chasing launch settings |
| Status lags behind the pedal | Switch adjustment at the pedal. It may only close at the very end of travel |
FAQ
SPI or AVI for a clutch switch?
Either works. We use an SPI when one is spare since the setup is simpler, and save AVIs for sensors that need a real analog reading.
Can the same wiring work for a brake switch?
Yes. The brake pedal switch is set up the same way, and the trans-brake is worth a look if you're setting up a drag car.
