Dongfeng VR truck parts SMJ box 3724421-C1100 in stocked

Designed as a centralized hub for critical electrical functions, the SMJ Box integrates multiple control modules to streamline the Dongfeng VR’s electrical system. It serves as a junction for three core functions: wiring harness distribution (managing power and signal flow to 8+ peripheral components like lights, wipers, and sensors), overcurrent protection (equipped with 6 built-in blade fuses rated 5A–20A to prevent circuit damage from overloads), and signal conversion (translating low-voltage sensor signals to the ECU for accurate data reading). The internal circuit board uses high-conductivity copper traces (0.2mm thickness) to minimize voltage drop, ensuring stable power supply to connected components. Unlike fragmented electrical setups with separate junction boxes and fuses, this integrated design reduces wiring clutter by 40%, simplifies troubleshooting, and lowers the risk of electrical failures

Engineered to withstand the harsh operating environment of trucks (exposure to rain, dust, road salt, and vibration), the SMJ Box features robust ingress protection. The housing is made of impact-resistant PA66 plastic (UL94 V-0 flame-retardant rating) with a one-piece sealed structure—all seams are filled with EPDM rubber gaskets that compress during assembly to block moisture and dust. The 16-pin connector is equipped with a rubber O-ring seal (70 Shore A hardness) that forms a tight barrier against water intrusion, even when submerged in 1m of water for 30 minutes (meeting IP65 standards). The box also has a pressure relief valve that prevents internal condensation by equalizing air pressure, avoiding corrosion of internal circuits. Unlike non-sealed electrical boxes that short-circuit in wet conditions, this design ensures reliable operation in rain, snow, or dusty off-road environments

Built to endure the constant vibration of truck frames and extreme temperature fluctuations, the SMJ Box uses durable materials and structural design. The internal circuit board is secured with 4 shock-absorbing silicone standoffs (8mm height) that reduce vibration transfer by 60%, preventing solder joint fatigue (a common cause of circuit failure). The housing tolerates a wide temperature range from -40°C (cold starts in winter) to 85°C (heat buildup in engine compartments), with all electronic components (fuses, capacitors, connectors) rated for the same temperature range to avoid performance degradation. The copper traces are coated with a 0.1mm conformal epoxy layer that protects against corrosion and insulation breakdown. Unlike fragile electrical boxes that fail under vibration or temperature stress, this design maintains functionality for 6+ years of heavy use

Designed for hassle-free service by fleet technicians or DIY owners, the SMJ Box simplifies installation and upkeep. It includes all necessary hardware: 4 M5×12mm stainless steel bolts, lock washers, and a foam padding sheet that reduces vibration when mounted on metal surfaces. Installation takes 15–20 minutes: locate the VR’s original mounting bracket, align the box’s holes with the bracket, torque the bolts to 8 N·m, and plug in the 16-pin connector (audible “click” confirms secure fit). Maintenance is tool-free: the top cover has a snap-on design that can be opened by hand to access fuses—no screws needed—making fuse replacement quick and easy. Each unit undergoes waterproof testing (IP65 verification), vibration testing (10–2,000 Hz for 2 hours), and electrical performance checks, backed by a 24-month warranty against defects (e.g., housing cracking, fuse holder failure, circuit board damage)