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The vehicle engineers responsible for designing computer control
systems programmed them so a scan tool could request information or
command a module to perform specific tests and functions. Some
manufacturers refer to bidirectional controls as functional tests, actuator
tests, inspection tests, system tests, or the like. Reinitialization and
reprogramming also can be included in the list of bidirectional controls.
Figure 4-16 Sample of the Actuation Test Menu
This function allows the device to send information to and receive
information from, vehicle control modules. For example, in the case of
OBD II generic information Mode 1 (which relates to data parameters),
the scan tool user initiates a request for information from the powertrain
