Diagnostic Trouble Codes (DTCs)

Each class 2 module stores DTCs as current or history DTCs. If the module detects a malfunction, it stores a DTC that corresponds to that particular malfunction. If the module stores a current DTC and the malfunction is no longer present, some DTCs will remain current until the next ignition cycle.

Other DTCs change from current to history without requiring a new ignition cycle when the fault is no longer present. History DTCs are intermittent malfunctions and must be diagnosed differently than current DTCs. Refer to Diagrams / Intermittents and Poor Connections Diagnosis.