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

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:
Cabling between the transmission output speed sensor and transmission controller.
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 controller and sensor.

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

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

Most of the fault locations can be connected with several fault types. Thus it is possible for two different fault causes that are related to each other to 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:
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, e.g. if a main cause for a fault type is known or there is additional experience from Voith Customer Service.

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

..are conditions that must be provided within the function software in order to evaluate the event setting conditions. Event test conditions e.g. engine running, vehicle moving, etc.