Scan Tool Diagnostics

Control modules connected to class 2 data bus can detect system malfunctions or abnormalities and set Diagnostic Trouble Codes (DTCs). When a malfunction occurs, a current DTC will be stored in the related control modules. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . Current DTCs indicate a control module has detected a fault or malfunction which is present during an ignition cycle. A history DTC indicates that a module has previously detected a current malfunction that is not present or no longer exists. Scan tool diagnostics should be used when checking for class 2 data bus circuit loss of communication codes (U1XXX), non-BCM related DTCs, and clearing DTCs (except BCM DTCs).