The following pieces of information must be obtained by the ELD for normal operation:
- Engine Power Status (eg Engine Power up/down)
- Vehicle Motion Status (eg Is the vehicle going above 5 mph?)
- Vehicle Miles (ie What is the odometer according to the vehicle's ECM?)
- Engine Hours (ie What is the current engine run time according to the vehicle's ECM?)
- Date and Time (ie What is the current date and time when a new event is recorded?)
- CMV Position (ie What is the current location of the vehicle when a new event is recorded?)
- CMV VIN (ie What is the VIN of the vehicle according to its ECM?)
If any of these values are not retrieved by the ELD, the ELD must record a "Data Diagnostic" event.
If a "Data Diagnostic" event lasts for long enough (for example, no location is retrieved for 30 minutes), the ELD must record a "Malfunction" event.
Usually the description of the "Data Diagnostic" event will include the reason for ELD issue (eg which of the 7 data types listed above is missing).
For example, in the following event, the issue is with the "Position" data. To resolve this, you can try to find a better position in the vehicle cabin where the tablet should be able to obtain a better GPS signal.