Safe to driveEnough to reach the yard
J1939 code SPN 520. Below — how the fault is worded at the factory by KAMAZ, MAZ, Renault Trucks and YaMZ, and what the second half of the code (FMI) means in the standard.
| FMI 11 | CAN: TSC1-TR timeout (SPN 520 — as listed in document) |
| FMI 12 | CAN: TSC1-TR timeout (SPN 520 — as listed in document) |
| FMI 11 | CAN message TSC1-TR error - CAN bus active message timeout. Blink code: 4-2-4. Repair: Check the CAN line connection to the other CAN devices. |
| FMI 12 | CAN message TSC1-TR error - CAN bus inactive message timeout. Blink code: 4-2-4. Repair: Check the CAN line connection to the other CAN devices. |
| FMI 9 | CAN data bus link to EECU, retarder. Repair: Check the continuity of the CAN bus connected to the EBS unit (X1/1, X1/3). Check that the engine control unit is connected and works correctly. |
| FMI 11 | TSC1-TR CAN message fault (Active CAN bus message timeout). Blink code: 4-2-4. Repair: Check the CAN line connection to the other CAN devices. |
| FMI 12 | TSC1-TR CAN message fault (Inactive CAN bus message timeout). Blink code: 4-2-4. Repair: Check the CAN line connection to the other CAN devices. |
| SPN 520 FMI 9520/9 · 520.9 | abnormal update rate |
| SPN 520 FMI 11520/11 · 520.11 | root cause not known |
| SPN 520 FMI 12520/12 · 520.12 | faulty device or component |
Safe to drive. Below — how much time you have and what happens if you keep going.
The modules have stopped hearing each other on the bus. Some dash readings are now made up and some functions are simply off.
You can physically drive, but do not trust the instruments, and the other codes in the list may well be false: fix the bus first, then look at the rest.
Check connectors and the harness: a broken CAN twisted pair takes out communication for every ECU at once.
This code is often not the fault itself but a knock-on. If any of these is in the same readout, start with it:
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.