Massey Ferguson 639.19 – Engine Control Unit (ECU): CAN BUS Fault (ECU) / Bus off Vehicle CAN (250k)

A critical communication failure where a module has gone 'Bus Off' on the 250k baud rate vehicle Controller Area Network (CAN). Electronic control modules cannot exchange information correctly, which can lead to engine power degradation, random dashboard warning lights, or a complete shutdown.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 7600 Series

1. 1

   Scan the system using an AGCO Electronic Diagnostic Tool (EDT) or compatible scanner to read all active and stored codes for secondary module faults.

2. 2

   Disconnect the battery and measure resistance between CAN High and CAN Low pins on the diagnostic port (should be approximately 60 ohms).

3. 3

   Inspect the ECU wiring harness for chafing, shorts to ground, or shorts to power.

4. 4

   Inspect ECU pins for moisture, corrosion, or bent terminals.

5. 5

   If CAN resistance is 120 ohms (one missing) or 0 ohms (short), test the terminating resistors individually.

1. 1

   Disconnect Power

   Always disconnect the battery before servicing ECU wiring or CAN bus components.

2. 2

   Clean Connections

   If corrosion or moisture is found at the ECU harness connectors, clean the pins thoroughly with electrical contact cleaner and apply dielectric grease.

3. 3

   Repair Harness

   If the diagnostic checks revealed a short or open circuit in the CAN wiring, splice and repair the damaged section of the harness according to OEM wiring diagrams.

4. 4

   Replace Resistors

   If a terminating resistor tested out of specification (not 120 ohms), replace the resistor plug.

5. 5

   Replace/Reprogram ECU

   If the wiring harness, connectors, and terminating resistors are all in perfect condition but the ECU still fails to communicate (internal CAN transceiver failure), the ECU must be replaced and reprogrammed using AGCO EDT software.