The scan tool displays module data. This information can assist in determining whether the module is operating properly and whether the module is sending or receiving the proper data to and from a particular system. The module uses data received from other systems in order to carry out some functions. Therefore, if the module receives incorrect data from another system, the module may seem to be functioning improperly. The scan tool can be used to review the data received from the systems that interact with the module to aid in the diagnostic process.

The scan tool also displays the modules input/output status. By selecting the modules input/output status display it can be determined if the switched inputs/outputs are being properly interpreted. The display also indicates if the input/output has changed states. For example, when a door is closed, the scan tool displays the input status of the door ajar switch as INACTIVE. When the door is open, the scan tool reads ACTIVE. This type of information can be used to help diagnose a malfunction associated with a particular system input or an input that is shared with another system.

The scan tool can be used to control some of the module controlled outputs on and off. This feature can be used to determine if the module is able to control an output regardless of the inputs to the module or any specific program instructions. Once a test is selected, the scan tool can command the module to control an output. The scan tool then displays the status of the selected output. Because the displayed status information represents only what the module was commanded to do, not what actually occurred, it is necessary to check that the module is actually performing each of the selected output functions.