Self-Diagnostic System: Notes

Body Control Module (BCM) is equipped with a self-diagnostic system, which detects system Diagnostic Trouble Codes (DTCs) or abnormalities. When a malfunction occurs, BCM will store a DTC. See BCM DTC DEFINITIONS. Malfunctions are recorded as history/intermittent failures or as current failures. Current DTCs indicate BCM has detected a fault which is currently present. A history DTC indicates that BCM has previously detected a malfunction that is not currently present.

A scan tool can be used to retrieve and clear DTCs. The scan tool also has several features that can be used to help locate an intermittent condition. When scan tool is used for system tests, it will display values actually seen or commanded by various systems (i.e., BCM, PCM). This will usually include the following types of information:

• Analog Data Input - Displays analog input seen by system.
• Inputs/Outputs - Displays digital values as seen by system, and provides indication of whether input or output has cycled.
• Special Functions (Output Controls) - Allows for outputs of system to be set at a desired value (ON or OFF). This will only indicate if BCM is sending the appropriate commands, not what action was actually taken.
• Clear Codes - Will erase DTCs for system currently selected (if problem still exists in system, DTC may immediately reset).