F 350 2WD Super Duty V8-5.4L SOHC VIN L (2002)
Speedometer Head: Description and Operation
Speedometer
The instrument cluster is hardwired to the four wheel anti-lock brake system (4WABS) module. The instrument cluster micro-processor monitors the
VSS data from the 4WABS module and commands the speedometer with a corresponding movement of the pointer. The vehicle speed signal is
generated by the rear anti-lock brake sensor and sent to the 4WABSs module. The 4WABS module sends the vehicle speed signal via circuit 679
(GY/BK) to all symptoms that require a vehicle speed signal input.
