Problem Diagnosis

Intermittent fault testing requires duplicating circuit or component failure to identify fault. These procedures may lead to computer setting a diagnostic trouble code which may help in diagnosis.

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

Use scan tool or DVOM to pinpoint faults. When monitoring voltage, ensure ignition is in ON position or engine is running. When monitoring resistance, ensure ignition is in OFF position or negative battery cable is disconnected. A status change on scan tool or DVOM while performing test procedures indicates area of fault. See TEST PROCEDURES  .