Car Tire Pressure Monitor System No Sensor Warning TPMS for Toyota Corolla Highlader for RAV4 Sienna Working principle: When the tire is underinflated, the tire radius becomes smaller and the wheel speed becomes faster; When the tire is overinflated,the tire radius becomes larger and the wheel speed becomes slower. The tire pressure monitor is connected to the CAV-OBD plugof the original vehicle computer data bus, reads the tire speed, and automatically monitors the original vehicle ABS data. When the tire is underinflated, it will cause abnormal data, and then the monitor will alarm. Classified alarm: When the tire pressure leak exceeds 25%, the value display 1.8,monitor alarm. When the tire pressure leak exceeds 50%, the value display 1.0,monitor alarm. Function ofF1-F7: factory default: F1=1, turn off unlock F1=0 (P file unlock) F2=1(Driving lock) F2=0 (D file lock) F3=1 (with reversing flashing light) F3=0 (no reversing flashing light) F4=1 (emergency brake flashing light, unlock) F4=0 (emergency brake no flashing light, unlock) F5=1 (Flashing light when opening the door) F5=0 (no flashing light when opening the door) F6=1 (handbrake flashing light) F6=0 (handbrake no flashing light) F7=1 (No self-locking when getting off) F7=0 (with self-locking when getting off)