This differential lock sensor (differential lock pressure switch) is an electrical signal component installed on the FAW heavy truck rear axle reducer. It detects the engagement state of the differential lock and sends feedback signals to the vehicle ECU and dashboard, lighting up the indicator lamp to remind the driver whether the differential lock is activated. With precision contact structure and zinc alloy shell, it maintains stable signal transmission under heavy vibration, mud splash and large temperature fluctuation during long-haul transport. The sealed internal structure prevents water and dust intrusion. Every sensor undergoes signal response and durability testing before delivery. It solves the problems of differential lock indicator failure, no signal feedback and misjudgment of lock status, serving as an important replacement spare part for heavy truck rear axle overhaul.