3/4″-16 Vehicle Speed Sensor Replacement Q21-6005 577.75500 577.59502 for Kenworth Peterbilt Trucks 1995-2011 Speedometer Tachometer

Product Overview The 3/4″-16 Vehicle Speed Sensor Replacement is a critical diagnostic component designed for Kenworth and Peterbilt Trucks (1995-2011). This versatile sensor is engineered to monitor and sync both speedometer readings and tachometer data (depending on specific model applications), providing real-time data to the vehicle’s instrument cluster, cruise control, and ECM. By ensuring precise transmission tailshaft speed tracking, it prevents erratic dashboard gauge behavior and cruise control dropouts, making it an essential maintenance replacement part for high-mileage commercial fleets. Technical Specifications Main OE Number: Q21-6005, Q216005 Interchangeable Numbers: 577.75500, 57775500, 577.59502, 57759502 Dorman / Other Reference: 505-5406, 505-5405, F238839 Thread Size: 3/4″-16 UNF Connector Option: Heavy-Duty Rectangular Connector Plug Function: Speedometer / Tachometer Speed Monitoring Transmission Application: Eaton Transmissions with Internal Tone Ring (Tail Shaft Mounted) Condition: 100% Brand New Premium Replacement Broad Vehicle Compatibility This sensor is specifically designed for the Paccar platform, primarily covering the following heavy-duty and medium-duty truck series built between 1995 and 2011: Series Compatible Models & Applications (1995-2011) Peterbilt Heavy Duty 357, 359, 362, 365, 367, 377, 378, 379, 384, 386, 388, 389 Series Kenworth Heavy Duty W900, W900B, T600, T600A, T660, T800, T2000, C500 Kenworth Medium Duty & Cabover T170, T270, T300, T370, K100, K300 Series Peterbilt Medium Duty 200, 210, 320, 330, 335 Series equipped with Eaton systems Key Benefits Dual-System Utility: Serves as a direct replacement for transmission-mounted sensing units providing speedo and tachometer signals. High Thermal Stability: Built with high-quality metal and rugged heatproof molded insulators to withstand prolonged exposure to high transmission temperatures. Precision Accuracy: Prevents “Gauge Drops to Zero” or needle jumping, ensuring your cruise control engages properly and the ECM logs no speed faults. Easy Installation: Direct-fit screw-in design (matches OE Q21-6005 / 577.75500 specs) requires no wiring modifications or special tools. Cross-Reference Guide This sensor interchanges with the following original and aftermarket part numbers: PACCAR / KENWORTH / PETERBILT: Q21-6005, Q216005, Q21-6005RT, AUTOMANN: 577.75500, 57775500, 577.59502, 57759502 DORMAN / DAYTON PARTS: 505-5406, 505-5405, 5055406, 5055405 OTHER CROSSES: Fortpro F238839, Freightliner 68154217, Mack 2515592 Maintenance Tip: If your Kenworth T300 or Peterbilt 379 shows erratic speedometer behavior or the cruise control fails to hold at highway speeds, check the tailshaft mounted sensor for dirt or metal shavings on the magnetic tip. Always verify your original pin configuration (2-pin or 4-wire) before ordering to ensure 100% correct setup.