How does Fiesta record and send speed and mileage

[borgward]

2013 Fiesta hatch SE hatch 5 Speed manual. How does it record and send speed and mileage? I saw reference that the sensor on the IB/5 transmission was for the speedpmeter/odometer. It was unplugged but speedpmeter and odometer still work. Traction stability control stays off.

 

[V70tdi]

A common way to read speed at european cars is from the ABS systems wheel speed sensors.

 

[mk378]

It's all linked together on the CAN bus. I suppose if the dash and PCM can't get road speed from the TCM it uses the ABS. ABS expects to monitor transmission output speed as well as each wheel or it can't be certain if there is a skid, so it reverts to uncontrolled brakes.