PERFECT FIT - 28146 Vacuum Pump Switch designed for electric vacuum pump for brakes. Compatible with AC Delco (Hella) vacuum pump and 79 Corvette, among other applications.WORKING VACUUM RANGE - The booster vacuum pump activates when vacuum levels fall below 0.04 MPa and deactivates at approximately 0.06 MPa. This switch automatically turns the pump on or off at a preset vacuum level, functioning as a pressure automatic adjustment switch.VACUUM PUMP SWITCH FUNCTION - Helps prevent continuous pump operation, extending pump lifespan. The switch controls the vacuum pumps on/off function and typically operates through a pilot relay connected between the switch and the pump motor.PRESSURE SWITCH AUTOMATIC ADJUSTMENT - The adjustment screw is secured with adhesive to prevent loosening during transit. The range is factory preset and not user adjustable. The switch will activate or deactivate the pump at the preset vacuum level.IMPORTANT TIPS - Ensure all connections are securely tightened to prevent leaks, which may affect pump performance. When installed correctly, the switch functions as intended. For support, please reach out through available customer service channels.Part Number: 28146Fit for: 28146 Electric Brake Vacuum PumpNote: This listing is for the switch only and does not include additional accessories. For the complete 28146 vacuum pump assembly, please refer to the appropriate product listing.Designed for reliable performance and compatibility with select vehicle models. Manufactured to meet quality standards for durability and function.