The PAS sensor tells your controller you're pedaling, so it can add motor power:
1. PAS 5V — low-voltage power from the controller. Never battery voltage — 36V/48V on this pin will fry the sensor.
2. PAS GND — the ground reference. A loose ground causes ghost assist that cuts in and out.
3. PAS SIGNAL — sends a pulse train as the magnets pass the pickup. No pulses = no assist.
4. Magnet disc gap — the disc must pass within a few millimeters of the pickup. Off-center after a crank removal? Assist dies until it's re-centered.
5. Quick test — lift the rear wheel, spin the cranks by hand, listen for kick-in. Silent = check the plug, then the disc, then the sensor.
6. Direction matters — most PAS discs are directional. No assist? The disc may be flipped.
Labels are functions, not wire colors — check your controller's label. Questions? Drop by the shop. ⚡