Protocol
J1939: diagnostics for trucks, buses and machinery
SAE J1939 is the family of CAN communication standards for trucks, buses and machinery: 29-bit identifiers, individually numbered parameters (SPN) and diagnostic messages such as DM1, which broadcasts active faults.
Reviewed by Daniel Morales, founder of Reprorace SL, on
Key facts at a glance
| Protocol | Standard | J1962 pins | Speed or link | ECO-LITE | ECO-LITE TOOL | ECOPRO Gen4 |
|---|---|---|---|---|---|---|
| J1939 | SAE J1939 | 6 and 14 or 3 and 11 (the 9-pin connector needs a cable) | 250 and 500 kbit/s | Yes: reading and PassThru | Yes, in PassThru | Not stated |
| CAN | ISO 15765-4 · ISO 11898 | 6 and 14 (2nd channel on 3 and 11; classic CAN on 1 and 9) | 125, 250 and 500 kbit/s | Yes: 2 channels and pins 1/9 | Reproduces the vehicle's | Multichannel |
Data from the device catalog and the standards cited. The devices are in pre-production: figures may be adjusted after the first units have been validated.
When you need it
- Trucks, buses and heavy vans running on 24 V
- Reading the active (DM1) and previously active faults of a commercial vehicle
- Running truck diagnostic software on your PC through a pass-thru interface
Which Diaglana device covers it, and its limits
- ECO-LITE
- Reads J1939 over CAN at 250 or 500 kbit/s, at 12 and 24 V with protection up to 36 V, and offers it in pass-thru mode. It only has the J1962 socket: the round 9-pin connector needs an adapter cable, which isn't included.
- ECO-LITE TOOL
- J1939 in pass-thru mode (J2534 and RP1210) for the software on your PC; 24 V on pin 16 needs a 100 W USB-C charger.
- ECOPRO Gen4
- 12 and 24 V commercial vehicles. In development.
Frequently asked questions
What is DM1?
The J1939 message each ECU uses to broadcast its active faults, each with its SPN (which parameter) and FMI (what kind of failure), plus the status of its warning lamps.
Does the 16-pin OBD socket work on a truck?
Many trucks have one. If yours only has the round 9-pin diagnostic connector, you need a cable from that connector to J1962; ask us before you buy.
Does it work with 24 V?
Yes. ECO-LITE works at 12 and 24 V, with input protection up to 36 V.
Has it been validated on trucks?
The devices are in pre-production: J1939 has been tested on a simulator, and validation on trucks is under way.
Want to try it in your workshop?
Check the device page for the full specifications, or buy in the shop at the final price.