Fault locations, fault types, previous fault types and action locations

The terms "fault location", "fault type" and "action location" define the place where a fault / event has occurred and what type of fault it is. These terms are frequently used in vehicle diagnosis, but they are not standardized. Especially regarding the fault location, a clear distinction must be made between the fault location and the action location.

The fault location describes the place where an event occurs. If a function or an element such as the speed sensor is defined as the fault location, all fault types that are connected to it are assigned to this fault location. That means the fault location does not yet determine what has caused the event.

Example of a fault location:

Transmission output speed sensor. This fault location indicates that some event or fault has occurred at the transmission output speed sensor.

The fault location describes where the event occurs.

The action location describes the exact place where the cause of an event is assumed to be. An event can have several action locations, if it cannot be clearly determined what the exact cause of the fault is.

Example of action location:

Cabling between transmission output speed sensor and transmission control unit.

For the fault location 'transmission output speed sensor', the action location specifies the exact place where the cause of the event is assumed to be. In this case, the cabling between the transmission control unit and the sensor.

The action location describes where the cause of the event is assumed to be.

The fault type describes as exactly as possible the cause of the fault, i.e., what has happened at the action location.

Example of fault type:

Short-circuit between ground and the positive terminal of the sensor.

The fault type describes what has happened.

Most of the fault locations can be put into relation with several fault types. Thus it may happen that two different fault causes that are related to each other occur subsequently in one fault location. In this case, both fault types are displayed in the "Fault type" and "Previous fault type" fields of the ECU report.

Example of previous fault type:

The fault location CAN protocol SAE J1939 detects a timeout of the CAN receive message 'Engine Configuration'. Shortly after that a timeout event of the CAN receive message 'EEC3' is detected. The 'EEC3' event will be displayed as the fault type and the 'Engine Configuration' event will be displayed as the previous fault type in the ECU report.

Additional information is displayed here, for example, if a main cause for a fault type is known or there is additional experience by the Voith customer service.

... are conditions that involve the signalling of an event within the function software.

..are conditions that must be provided within the function software in order to be able to evaluate the event setting conditions. Event test conditions are, for example: engine running, vehicle in drive etc.

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