The 550 will get its speed information from the ABS system, monitoring the speed at which all 4 sensors are rotating, taking the closest average, providing this information to the ECU for odometer, tripmeter and a calculated (over time) speedometer reading.
The boxes that you can buy in Jaycar and the like that modify the incoming signal by a small degree work with a revolution sensor. The 550 will have one on the output of its transmission, but that'll be used for the gearbox's computer, it won't be used for the distance (and as a result, distance over time = speed) measurement.
The boxes that you can buy in Jaycar and the like that modify the incoming signal by a small degree work with a revolution sensor. The 550 will have one on the output of its transmission, but that'll be used for the gearbox's computer, it won't be used for the distance (and as a result, distance over time = speed) measurement.
