Intermittent and History DTCs

History DTCs are codes indicating that the BCM previously detected a fault which later-disappeared. Any DTC beginning with the digit 3 is a "History" DTC. Examples are: 31 32, 33 etc. The reason could be either that the fault is an intermittent failure, or that the faulty system is not currently being operated.

If the cause of the failure cannot be identified through visual (physical) inspection, the vehicle can be driven with a DVM connected to the suspected circuit An abnormal voltage or resistance reading when the failure occurs indicates the problem may be in that circuit.