3/4″-16 Dual 4-Wire Vehicle Speed Sensor Replacement Q21-6004 577.59502 577.75500 for Kenworth Peterbilt Speedometer Tachometer T270 T300 T370

Product Overview The 3/4″-16 Dual 4-Wire Vehicle Speed Sensor is a critical diagnostic component designed for Kenworth and Peterbilt Trucks. 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. By ensuring precise transmission speed tracking, it prevents erratic dashboard gauge behavior and cruise control failures, making it an essential maintenance replacement part for high-mileage commercial fleets. Technical Specifications Main OE Number: Q21-6004 Interchangeable Numbers: 577.59502, 577.75500, Q216004, 57759502, 57775500 Thread Size: 3/4″-16 UNF Wiring Configuration: Dual 4-Wire / 4-Pin Plug Function: Speedometer / Tachometer Speed Monitoring Connector: Standard Heavy-Duty Sealed Plug 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: Series Compatible Models & Applications Kenworth Medium Duty T170, T270, T300, T370 Series (Speedo / Tachometer systems) Kenworth Heavy Duty W900, W900B, T600, T600A, T660, T800, T2000, C500 Kenworth Cabover K100, K300 Series (Eaton Transmission Applications) Peterbilt Trucks Various models equipped with Paccar/Eaton dual speedo & tach systems Key Benefits Dual-System Utility: Serves as a direct replacement for both speedometer and tachometer sensing units in Eaton transmission systems. High Thermal Stability: Built to withstand prolonged exposure to high transmission oil temperatures and harsh under-vehicle road environments. Precision Accuracy: Prevents erratic gauge needle jumping and “False Speed Sensor Fault” dashboard warnings, ensuring consistent cruise control operation. Easy Installation: Direct-fit design (matches OE Q21-6004 / 577.59502) requires no wiring modifications or special tools for setup. Cross-Reference Guide This sensor interchanges with the following original and aftermarket part numbers: PACCAR / KENWORTH / PETERBILT: Q21-6004,Q216004 AUTOMANN: 577.59502, 577.75500, 57759502, 57775500 COMPATIBLE HARNESS / OTHERS: 577.756970, W094118, Freightliner 68154217, Mack 2515592 Maintenance Tip: If your Kenworth T300 or Peterbilt shows erratic speedometer behavior or a “Speed Sensor Fault” after a transmission service, check the sensor’s 4-wire connector for dirt or corrosion. We recommend verifying the 3/4″-16 thread clearance whenever the sensor is replaced to prevent transmission fluid leaks.