Intermittent failures in electronic systems may be difficult to detect and accurately diagnose. The SBM tests for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a fault condition. If the system malfunction does not repeat during the drive test, a good description of the complaint may be useful in locating an intermitting fault condition. Faulty wires or connections cause most intermitting problems. When an intermitting condition is suspected, inspect the suspected circuits for the following conditions:

History DTCs indicate that the SBM previously detected a malfunction. The malfunction detected may indicate one of the following possibilities:

If the SBM displays history DTCs and the malfunction cannot be found easily, complete the following actions:

1. Clear the DTCs.
2. Use a scan tool in order to manually operate the system that the DTC applies to.

History DTCs help in diagnosing intermittent fault conditions, but they do not necessarily indicate a faulty SBM. The SBM is a reliable component that is not likely to cause the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to a faulty component. Thoroughly inspect all related wiring and connectors pertaining to the history DTC that is stored.

The following conditions may result in intermittent SBM operation with no DTC stored: