## Common ground
All options describe ABS sensors used in vehicles to monitor wheel rotation for safety systems.
## Options at a glance
**8543.70 – Wheel speed signal senders**
- **Defining trait:** Transmits raw data (speed, direction, position) to an ECU without processing or measuring.
- **Typical examples:** Magnetic pickup sensors in brake hubs, Hall effect sensors sending pulses.
- **Best fit when:** The sensor only sends signals; no internal measurement or calculation occurs.
**9029.10 – Revolution counters**
- **Defining trait:** Functions primarily as a counting device for wheel rotations, not for precise speed measurement.
- **Typical examples:** Simple pulse generators used in odometers or basic rotation tracking.
- **Best fit when:** The sensor’s main role is counting revolutions, not measuring speed or direction.
**9031.80 – Precision speed measurers**
- **Defining trait:** Designed to measure and supply accurate wheel speed data directly to the ABS ECU.
- **Typical examples:** High-resolution Hall effect or variable reluctance sensors with signal conditioning.
- **Best fit when:** The sensor includes internal processing for precise, real-time speed data.
## Key differences
| Feature | 8543.70 | 9029.10 | 9031.80 |
|---------------------|------------------------|-----------------------|-------------------------|
| Measurement role | Signal transmission only | Counts rotations | Measures speed precisely |
| Data processing | None | Minimal | Internal processing |
| Primary function | Communication | Counting | Precision sensing |
## How to choose
- Does the sensor only send raw pulses (no measurement)? → 8543.70
- Is it used mainly to count wheel rotations (e.g., for odometer)? → 9029.10
- Does it provide accurate, real-time speed data with signal processing? → 9031.80
## Overlaps & pitfalls
A sensor may fit multiple categories if it counts rotations *and* sends speed data. The key is the **primary function**: if it’s for precise speed control in ABS, use 9031.80. If it only transmits signals without measuring, use 8543.70. If it's used for counting only, use 9029.10. No option is clearly prioritized—choose based on the sensor’s **main purpose** in the vehicle system