Programming the speedometer: Notes

The ABS or TC/ABS control module reads 29 pulses per wheel revolution. Depending on the size of the tire and rim (physical circumference), one kilometer will correspond to a different number of pulses when the main instrument unit receives the value from ABS or TC/ABS. It is therefore possible to change how the main instrument unit interprets the total number of pulses per kilometer to correspond to the tire size fitted on the car. this must be programmed so that the speedometer and the odometer give the driver the correct information. It is compulsory on several markets that the speedometer shows speeds between 0 and 10 km too high.

NOTE: If the speedometer is not programmed correctly, the speed displayed for the driver may be lower than the actual speed and SID will provide incorrect information concerning fuel quantity and arrival time.

Fig 1: Identifying Speedometer

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Identifying Dimensions Of Tire

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The current tire size is programmed using Tech 2. There are three possible types of tire to choose from. Tire type 1 has the largest circumference and tire type 3 has the smallest.

If the speedometer is programmed for a certain type of tire and new wheels with a larger circumference are fitted, the speed displayed by the speedometer will be too low.

IMPORTANT: The car must be approved for fitting 17" wheels.