How does my ecu know how fast I'm going?
#10
VSS is useful for a lot of things in modern ECUs. Stability control, traction control, cruise control, airbag management, boost-by-gear (divide speed by RPM and you can figure out what gear it's in), all kinds of stuff relating to automatic transmission control, the list goes on.
As for your NA, yes, the speedo cluster converts the mechanical wire into an electrical signal and sends it to the ECU. Many of the above don't apply to an NA, but it's still useful in an OBD-2 ECU for debugging issues in the car -- VSS gets stored along with the other freeze frame data, which may help someone figure out what triggered the code.
--Ian
As for your NA, yes, the speedo cluster converts the mechanical wire into an electrical signal and sends it to the ECU. Many of the above don't apply to an NA, but it's still useful in an OBD-2 ECU for debugging issues in the car -- VSS gets stored along with the other freeze frame data, which may help someone figure out what triggered the code.
--Ian