In my search for information on HOW my Subaru determines speed, I have come across the following document.
Page 8 covers section D) Speedometer.
Page 10 covers section E) Vehicle speed sensor.
I hope this is of some use to you all.
- The speedometer system is an electrical type that uses electric signals from the speed sensor in MT models or the transmission control module in AT models.
- The vehicle speed sensor is installed on the manual transmission.
- Since the system does not use mechanical components such as rotating cable, there are no opportunities of occurring such problems as meter needle vibration and cable disconnection. Also, it does not constitute any means of mechanical noise transmission.
MT models: The vehicle speed sensor sends vehicle speed signals (4 pulses per rotation of speed sensor’s driven shaft) to the speedometer drive circuit and odometer/trip meter drive circuit in the speedometer.
AT models: The TCM sends vehicle speed signals (4 pulses per rotation of output shaft) to the speedometer drive circuit and odometer/trip meter drive circuit in the speedometer.
NOTE: Signals from the speed sensor or TCM are also used by the engine control module, automatic transmission control module, etc.
Example: Needle points to 60 km/h (37.3 MPH) when 2,548 pulses are input per minute.
All in this document:
01._Combination_Meter.Pdf 479.38KB
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