The speed sensor is located on top of the rear differential.
Programmable Speedometer/Odometer Module (PSOM)
The programmable electric analog speedometer receives its input from the anti-lock brake sensor except on F-Super Duty Motorhome Chassis where it receives its input from the park brake-mounted speed sensor. The liquid crystal display (LCD) odometer is a combination trip odometer and total odometer. The total odometer is normally displayed. To see the trip odometer, press and release the SELECT button on the upper right side of the speedometer. To zero out the trip odometer, press and release the RESET button on the upper left side of the speedometer while the trip odometer is displayed. If the trip odometer is displayed, press and release the SELECT button to return the display to the total odometer value. The speedometer, containing the trip odometer and total mileage odometer, is serviceable only as an instrument cluster (10849) assembly.
Federal law requires that the odometer in any replacement speedometer must register the same mileage as that registered on the removed speedometer/odometer. Service replacement speedometer/odometer and odometer modules with the mileage preset to actual vehicle mileage are available through Ford Electronic Service Centers. In nearly all instances, the mileage continues to accumulate in the odometer memory even if the odometer does not display mileage. This mileage can usually be verified by the electronic service centers. Contact the service center for instructions to receive a replacement speedometer/odometer or odometer module with the mileage preset to actual mileage.
If the actual vehicle mileage cannot be verified, the service center will supply a speedometer/odometer module with the odometer display preset to zero ("0") miles and the service odometer segment ("s") illuminated in the vicinity of the odometer display. In addition, an odometer mileage sticker is supplied with the replacement odometer. This sticker must display the estimated vehicle mileage and is to be affixed to the driver's door.
NOTE: Before ordering an instrument cluster (10849), contact the instrument cluster technical hotline for diagnostic and system troubleshooting assistance. The hotline phone number is XXXXX
The speedometer is also used to provide a speed signal for correct operation of the vehicle's powertrain control module (PCM) (12A650), transmission (7003), and speed control (if so equipped). Because of this, it is VERY IMPORTANT to change the speedometer's internal conversion constant if the size of tires on the vehicle is changed. Changing the conversion constant to the proper value when the tires are changed will also make sure that the speedometer retains the original factory-set accuracy. The conversion constant can only be changed six times once the vehicle leaves the factory. On F-Super Duty Motorhome Chassis the conversion constant must never be changed. If tires or rear axle ratio is changed, the gear in the transmission drive gear must be changed.