Intermittent Problem Diagnosis

Intermittent fault testing requires the duplication of circuit or component failure, in order to identify the fault. These procedures may lead to the computer recording a fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, it will be necessary to monitor voltage or resistance values using a DVOM while attempting to reproduce conditions which will create an intermittent fault. A change in status on the DVOM will indicate a fault has been located.

When using a voltmeter to pinpoint faults, monitor voltage reading with ignition on, or vehicle running. A change in status on the voltmeter while performing test procedure will indicate area of fault. See TEST PROCEDURES under INTERMITTENTS in this article.

When using an ohmmeter to detect problems in the circuit, monitor circuit resistance (ohms) with ignition switch in the OFF position, or with battery disconnected. A change in ohmmeter reading while performing test procedure will indicate area of fault. See TEST PROCEDURES under INTERMITTENTS in this article.