Vehicle Speed Sensors

Vehicle Speed Sensors


Vehicle Speed Sensors (VSS) can be used for multiple purposes. Besides datalogging, vehicle speed sensors are used for Fuel and Ignition Tuning, Traction Control, Idle Control, Boost Control, Gear Detection, and many other purposes. Up to 4 Wheel Speed Sensors and a Drive Train Sensor can be used, and these can be either wired to the ECU or received via CAN with supported vehicles.

NOTE: Traction control for Front Wheel Drive requires at least one front wheel sensor (or drive train sensor) and at least one rear wheel speed sensor. Traction control for Rear Wheel Drive requires at least one rear wheel sensor (or drive train sensor) and at least one front wheel speed sensor. Traction control for Four Wheel Drive requires at least two speed sensors. Any combination of the following is acceptable: at least one rear wheel and the drive train, at least one front wheel and the drive train, or at least one front wheel and one rear wheel.


Sensor Speeds

Calibration Speed - The speed that the vehicle must be moving precisely at when each sensor is to be calibrated.
Drive Train Sensor and Wheel Speed Sensors - With the vehicle travelling at exactly the same speed as has been entered for the Calibration Speed, press Calibrate for each of the enabled sensors. For digital inputs, the ECU will measure the Pulses/km or Pulses/Mile for each sensor accordingly. This value can be manually entered if it is known. If the vehicle Speed Inputs are CAN, the ECU will measure the percentage change for each sensor during the calibration stage. This can compensate for changes in wheel rolling diameter.

Drive Shaft RPM Sensor

Available only when a Drive Train Sensor is enabled in the Wiring Tab.

Number of Teeth - The number of teeth per driveshaft revolution. This will be consistent with the number of magnets in the driveshaft RPM collar. Typically this will be 2, 8 or 12.
Max Derivative - The maximum rate of change for the driveshaft RPM. This filters out any spikes in signal due to noise.
Warning Maximum - When the Driveshaft RPM reads above this amount, any relevant items on the ESP software will flash Red as a warning of high RPM.

Derived Channels



Derived Channels

Driven Wheel Speed Calculation Method - This sets whether the Driven Wheel Speed Channel uses the average of all driven wheels or the wheel speed of the fastest driven wheel.
Undriven Wheel Speed Calculation Method - This sets whether the Undriven Wheel Speed Channel uses the average of all undriven wheels or the wheel speed of the fastest undriven wheel.

Diagnostics



This node enables or disables the diagnostics for each enabled wheel speed sensor, as well as conditions where there is variation between the wheel speed sensors.
A DTC severity can be set, which will trigger an Engine Protection level for the relevant setting.

Diagnostic Trouble Codes will be activated under the following conditions:

If 1 or 2 sensors
* Vehicle speed is 0
* TPS is below User Demand Minimum setting and
* MAP is less than -60 kPa and
* RPM is between 2000 and 5000 RPM and
* The above conditions have been true for more than 10 seconds 
If more than 2 sensors
* The RPM is less than 4000 and
* TPS is less than 20%
* And the speed is more than 15km/h different from the average of all the vehicle speed sensors

Vehicle Speed Filter



Wiring




Options

Main Source - Select the sensor that is to be used by the ECU for general use Vehicle Speed. This will be used by various ECU functions that require a vehicle speed.
Sensors - Enable any sensors that are required, and select if the sensor is wired to the ECU or is input via CAN.

Connections

Select between a Digital Frequency or CAN Input. When Digital Frequency is used as the type of sensor, select an appropriate input to use for each of the enabled Vehicle Speed Sensors. An SPI (Synchronised Pulsed Input) should be used.
Edge Select - Select the edge of the signal to be used. Typically this will be Falling unless instructed otherwise.
Sensor Type - Select if the sensor being used is a digital Hall Effect or a reluctor sensor.
Pull Up - Some Hall Effect sensors require a Pull Up if it is not incorporated in the wiring or the sensor itself. Enable as required.

Arming Voltage

The Arming Voltage table will be enabled if the input is an SPI, and the Signal Type is Reluctor.


This table is used to set the voltage threshold at which the ECU will start listening for the activation edge on the input signal.

Glitch Filter

The Glitch Filter table will be enabled if the input is an SPI.


This table sets the amount of time in microseconds that the signal pulse must remain in a transitioned state in order for the signal to be accepted as valid. 
Any pulse shorter than this time will be considered a glitch on the signal and rejected by the ECU.


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