Intermittent Problem Diagnosis

Intermittent fault testing requires duplicating circuit or component failure to identify the problem. These procedures may lead to the computer setting a fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, monitor voltage or resistance values using a DVOM while attempting to reproduce conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.

When using a DVOM to pinpoint faults, monitor voltage reading with ignition on, or vehicle running. Ensure ignition is in OFF position or negative battery cable is disconnected when monitoring circuit resistance. Changes in ohmmeter reading while during test procedures indicates area of fault.