Toyota Sienna Service Manual: Speed sensor check (when using intelligent tester)
(a) Check the backward signal.
(1) Drive the vehicle in reverse for more than 1 second at 3 km/h (2 mph) or higher.
HINT: Drive the vehicle in reverse and check the speed sensor signal. Note that the signal check cannot be completed if the vehicle speed is 45 km/h (28 mph) or more.
(b) Check the forward signal.
(1) Drive the vehicle straight forward. Drive the vehicle at a speed of 45 km/h (28 mph) or higher for several seconds and check that the ABS warning light goes off.
HINT: The signal check may not be completed if the vehicle has its wheels spun or the steering wheel turned during this check.
(c) Stop the vehicle.