DM1 / FECA (DM1)
Know which vehicle faults need attention
Modern commercial vehicles continuously monitor their own electronic systems.
When an active diagnostic fault is detected, the vehicle can broadcast a J1939 DM1 message containing information about the affected component, the type of failure and the severity of the warning.
The Squarell DM1 / FECA Parameter Group converts this diagnostic information into a structured Active DTC message, making active vehicle faults immediately available to fleet management, maintenance and remote diagnostic applications.
Specifications
Name: DM1 / FECA
Header: $ActiveDTC
Subscription: Yes
Solution: Uptime
Trigger: On Receive DM1
Output port: Selectable
Typical Applications
The DM1 / FECA Parameter Group supports applications such as:
- Remote vehicle diagnostics
- Active fault monitoring
- Predictive maintenance
- Workshop planning
- Fleet health dashboards
- Breakdown prevention
- Maintenance alerts
- Vehicle uptime management
- Technical support
- Fault history analysis
Key Parameters
Diagnostic Status
Before looking at individual faults, the message provides an immediate indication of their severity.
Typical parameters include:
- Source Address of Sender
- Malfunction Indicator Lamp Status
- Red Stop Lamp Status
- Amber Warning Lamp Status
- Protect Lamp Status
These statuses allow an application to distinguish between an informational diagnostic event and a fault that may require immediate action.
Active Diagnostic Trouble Codes
A single DM1 message can contain multiple active faults.
The Squarell Parameter Group reports up to 10 active error parameters, each containing:
- Parameter Number
- Failure Mode Indicator
- Number of Times Error Occurred
Together these values identify what is affected, how it has failed and how often the fault has occurred.
From SPN and FMI to useful information
In J1939 diagnostics, a fault is normally described by an SPN (Suspect Parameter Number) and FMI (Failure Mode Identifier).
The SPN identifies the parameter or component associated with the fault, while the FMI describes the type of failure.
For example, the failure may indicate that a value is:
- Above normal operating range
- Below normal operating range
- Mechanically incorrect
- Electrically open or shorted
- Not responding correctly
- Providing invalid data
Combined with the occurrence count, this gives maintenance applications considerably more information than a simple dashboard warning.
The complete Parameter Group and parameter definitions are available to Squarell partners.
Visualisation
DM1 information is particularly suitable for a fleet health dashboard.
Instead of simply showing that a vehicle has a warning, an application can display:
Vehicle → Warning Severity → Component → Failure Mode → Occurrence Count
This allows a fleet manager or workshop to quickly identify which vehicles require attention and prioritise maintenance accordingly.
Business Value
The DM1 / FECA Parameter Group helps fleet operators to:
- identify active vehicle faults remotely
- detect problems before vehicles return to the workshop
- prioritise faults according to severity
- improve workshop preparation
- reduce diagnostic time
- prevent avoidable roadside breakdowns
- improve preventive maintenance
- increase vehicle availability
A workshop can therefore know what is wrong before the vehicle arrives, allowing technicians, diagnostic equipment and potentially required parts to be prepared in advance.
Why Squarell?
J1939 diagnostics provide valuable technical information, but interpreting raw diagnostic messages requires knowledge of SPNs, FMIs, source addresses and vehicle-specific implementations.
Squarell converts this information inside the IVMS into a structured Active DTC message that can be used directly by fleet and maintenance applications.
This gives applications consistent access to diagnostic information without having to process the original J1939 DM1 communication themselves.
