F 250 2WD Super Duty V8-7.3L DSL Turbo VIN F (1999)
Vehicle Speed Sensor: Description and Operation
The Vehicle Speed Sensor (VSS) has been deleted for 1999. On vehicles equipped with 4-Wheel Anti-Lock Brake Systems (4WABS), the vehicle speed
signal is generated by the rear anti-lock brake sensor and sent to the 4WABS module. The 4WABS module sends the vehicle speed signal via circuit 679
(GY/BK) to all systems that require a vehicle speed signal input. Vehicles equipped with Rear Anti-lock Brakes (RABS) generate a vehicle speed signal
from the rear axle speed sensor. The Generic Electronic Module (GEM) receives this signal (VSS_GEM) for internal use and then distributes it to the
appropriate other users (i.e., the Powertrain Control Module [PCM], speed control module, and speedometer).
