What a steering angle sensor is for
The sensor reports the steering wheel's position, the angle it is turned to, and how fast it is moving. Factory systems use it to help stability control, braking and traction decisions as the car changes direction. Some variable-assist power steering systems use it to change hydraulic assist. On a Haltech Elite, bringing that signal in means you can log it alongside everything else and build strategies around it, for example comparing steering input with throttle and wheel speed when you're chasing handling or traction issues.
Wiring tab: choosing the input
You can connect the sensor to two types of Elite input. An AVI (analog voltage input) is the first choice. If you've run out of AVIs, an SPI (synchronized pulsed input) will also work.
| Input | When to use it | Settings | Our advice |
|---|---|---|---|
| AVI | The recommended option | Pull up: enables a 1k resistor to 5 V | Disable for a powered sensor with its own supply |
| SPI | No AVIs left | Sensor Type: Hall Effect for analog inputs. Pull up: a weak 10k resistor to 5 V | Use Hall Effect as the sensor type, and disable the pull-up for a powered sensor |
Pull-up or not?
The pull-up is there for sensors that don't make their own voltage. A two-wire temperature sensor is the classic example: it's just a variable resistor, so the ECU has to provide a supply through a pull-up. Steering angle sensors are normally powered and drive their own output signal, so in most cases the pull-up should be off. The other time to turn it off is when the sensor is shared with another ECU, such as a piggyback install alongside the factory computer. The other ECU usually already provides the pull-up, and adding a second one would shift the reading.
Calibration tab
The ECU needs to know how voltage turns into steering angle. ESP ships with a number of pre-built steering angle calibrations. Use the yellow folder icon at the top left of the tab to load one, and the blue disk icon next to it to save your own.
If your sensor isn't in the list, build a custom calibration from the manufacturer's data sheet: the output voltage at known angles. Once it's in, check it on the car:
- With the wheels straight, confirm the reading is at or near zero.
- Turn to full lock each way and check the reading moves the right direction and reaches a sensible angle.
- Save the calibration to a file so you can reuse it.
Display tab: catching wiring faults
Most analog sensors never sit right at 0 V or 5 V in normal use. A reading stuck at either end usually means a broken wire or a short. The Raw Min and Raw Max settings use that to detect faults:
| Setting | Fault code | Triggers when | Default |
|---|---|---|---|
| Raw Min | C1030 | Voltage drops below the value you set | Disabled |
| Raw Max | C1031 | Voltage goes above the value you set | Disabled |
To set them, watch the raw voltage at both full locks, then set Raw Min a little below the lowest reading and Raw Max a little above the highest. If you use engine protection, you can also give each fault a severity level so the ECU responds to it. For a steering sensor, most people just log the fault rather than cut power.
Troubleshooting
| Symptom | Usually |
|---|---|
| Reading stuck at maximum | An open signal wire, or a signal shorted to the 5 V supply |
| Reading stuck at zero | Signal shorted to ground or no sensor supply |
| Angle moves the wrong direction | Calibration slope reversed |
| C1030 or C1031 set with the sensor working | Raw Min or Max set too close to the real operating range |
For more on the input types, see brake pressure sensors and other sensor setups in the Elite function list, or browse the knowledge base.
FAQ
Can I share the factory steering angle sensor with the OEM systems?
Often, yes, if it's an analog output. Disable the Haltech pull-up so it doesn't load the signal the factory ECU is already reading.
My sensor isn't in the ESP calibration list. What now?
Create a custom calibration from the manufacturer's voltage-versus-angle data, or ask us and we'll help you work it out.
