New Holland ENG 426 – Engine Controller (ENG / ECM): J1939 data link cannot transmit

Controller Area Network (CAN bus) communication failure. The Engine Control Module (ECM) has started communicating with other devices on the SAE J1939 data link but has lost the ability to transmit messages. This can be caused by an intermittent electrical issue in the J1939 wiring, another device on the network tying up communications, or an electronic service tool being unplugged improperly before the ECM was keyed off.

• T7 series
• T7.270
• T8 series
• T8040
• T9 series
• TM series
• TM 175
• CR series
• CR9090
• CX series
• CX8080
• CX8090
• FR series
• FR450
• Magnum
• Steiger
• Puma

1. 1

   Verify battery voltage and connections. Low voltage or poor grounds can cause modules to drop off the data link.

2. 2

   Inspect the OEM wiring harness and ECM connectors for corroded, bent, broken, pushed-back, or expanded pins.

3. 3

   Check for moisture, dirt, or missing connector seals on the ECM and J1939 diagnostic ports.

4. 4

   With the key OFF and batteries disconnected, measure the resistance across the J1939 CAN High and CAN Low pins. A healthy network should read approximately 60 ohms.

5. 5

   Disconnect other modules (e.g., transmission controller, armrest module, instrument cluster) one at a time to see if communication is restored to the ECM.

1. 1

   Turn the key switch to the OFF position and disconnect the machine's battery to prevent electrical spikes.

2. 2

   Locate the Engine Control Module (ECM) and the main J1939 data link harness.

3. 3

   Disconnect the ECM harness connectors. Clean any dirt, debris, or light corrosion from the pins using an approved electrical contact cleaner.

4. 4

   If any pins are bent, pushed back, or broken, repair the connector using a pin extraction/replacement tool.

5. 5

   Inspect the main J1939 backbone wiring for chafing, particularly where the harness routes near the engine block or articulation points. Repair any damaged CAN High or CAN Low wires using twisted-pair repair best practices.

6. 6

   If the CAN bus resistance test failed, locate and replace the faulty J1939 terminating resistor.

7. 7

   Reconnect all harness connectors securely, ensuring the weather seals are seated properly.

8. 8

   Reconnect the battery and turn the key switch ON.

9. 9

   Connect an electronic service tool (such as CNH EST or Cummins INSITE) and clear the inactive fault codes.

10. 10

    Cycle the key and verify that Fault Code ENG 426 does not return. If the wiring is perfectly intact and the code persists, the ECM itself may have a hardware failure and require replacement or reflashing.