Why log brake pressure?
A brake light switch only tells you the pedal moved. A pressure sensor tells you how hard. On a track car, front and rear brake pressure in the log shows you braking points, peak pressure, how smoothly the driver releases into the corner and how the bias is actually working. Put it next to speed and G-force and you can see whether a lap was lost on the brakes.
On an Elite ECU, the brake pressure inputs are used for datalogging and can also tie into engine protection through their fault codes. Front and rear are set up the same way, each on its own input.
The sensor
Brake pressure sensors are powered sensors with three wires: a 5V supply, a signal back to the ECU and a signal ground. ESP's default calibration is for the Haltech 2000 psi brake/nitrous pressure sensor, which is what we fit on most builds. It covers the pressures a typical hydraulic brake system sees with room to spare, and the calibration is ready to go.
Mount it in the brake line with fittings rated for brake pressure, and bleed the system properly afterward. A sensor at the end of a tee on the front circuit and another on the rear circuit gives you both channels.
Wiring tab: choosing an input
You can use either an AVI or an SPI. An AVI is the better choice. Use an SPI only if you've run out of AVIs.
| Input type | Settings to check | Our advice |
|---|---|---|
| AVI (Analog Voltage Input) | Pull up: switches in a 1k resistor to 5V | Pull up off. The sensor drives its own signal, and a pull-up will skew the reading |
| SPI (Synchronized Pulsed Input) | Sensor Type, and Pull up (a weaker 10k resistor to 5V) | Set Sensor Type to Hall Effect, as for any analog signal on an SPI, and leave the pull-up off |
The pull-up is there for two-wire sensors like temperature senders that don't produce a voltage of their own. A three-wire pressure sensor has its own supply, so it doesn't need one. The same goes if the sensor is shared with another ECU, such as a factory ECU in a piggyback setup, because that ECU usually provides any pull-up already.
Calibration tab
ESP ships with a set of pressure sensor calibrations. Use the yellow folder icon to load one, and the blue disk icon to save your own. If your sensor isn't listed, you can build a custom calibration from the manufacturer's voltage-to-pressure data. Once you've made one, save it so you can reuse it on the other channel or the next car.
A quick sanity check: with the system at rest and the pedal off, the reading should sit near zero. Press the pedal firmly and it should climb smoothly and return when you let go.
Display tab: warnings
- Warning Minimum: below this pressure, brake pressure displays in ESP flash red.
- Warning Maximum: above this pressure, they flash red.
These only change how the value looks in the software. They're useful while testing, for example to catch a sensor that isn't returning to zero, but they don't do anything to the engine.
Diagnostics tab: catching wiring faults
A sensor like this normally outputs a voltage somewhere in the middle of its range. If the signal sits right at 0V or right at 5V, something has usually gone wrong: a broken wire, a short or a failed sensor. The diagnostics let the ECU spot that:
| Setting | Fault code | Triggers when |
|---|---|---|
| Raw Min | C1020 | Signal voltage falls below the value you set |
| Raw Max | C1021 | Signal voltage rises above the value you set |
Both are disabled by default. With the Engine Protection function active, you can give each code a DTC severity level to decide how the ECU reacts. Pick thresholds just outside what a healthy sensor ever produces, check them against your logs, and avoid anything so tight that normal readings trip it.
Troubleshooting
| Symptom | Usually |
|---|---|
| Reads high with no pedal | Pull-up enabled on the input, or wrong calibration loaded |
| Stuck at a fixed value | Open signal wire, or no 5V supply to the sensor |
| Noisy or jumpy trace | Poor ground, or signal wire run alongside ignition wiring |
| C1020 or C1021 set | Wiring fault or failed sensor. Check voltage at the plug |
| Reads fine, then wrong after bleeding | Air trapped at the sensor. Bleed at the sensor if you can |
Brake pressure FAQ
Do I need both front and rear sensors?
One front sensor tells you most of what you want about driver technique. Adding the rear shows your real brake bias, which matters if you run a bias adjuster.
Can I use the brake pressure signal as a brake switch?
A dedicated brake pedal switch input is the simpler way to tell the ECU the brakes are on. Pressure is best for logging and analysis.
Setting this up on a Nexus?
The idea is the same in NSP. See brake pressure (front).
