Scan Tool Data Display

When diagnosing a system which relies on the operation of a control module using the class 2 serial data circuit, a scan tool may be used to view data which affects system operation. A control module usually relies on several inputs to carry out a certain output function. System operation may be determined by input devices such as switches or sensors wired directly to the control module which is performing an output function. A control modules output functions may also be affected by information provided by other control modules using the serial data circuit. A scan tool can provide access to this information and may be necessary to determine why a system malfunction exists.