Massey Ferguson 000639.19 – ECU: Vehicle CAN Bus Communication Failure

The system has detected a fault in the CAN BUS communication related to the ECU, specifically a very high error rate on the primary vehicle CAN bus (250K). This indicates that the network is either completely non-functional or experiencing such a high volume of corrupt data that communication between control modules is impossible. This fault affects the ability of the ECU to communicate with other essential components in the system.

• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
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• 7626

1. 1

   Check battery voltage (approximately 12.6V with the engine off) and load-test the battery to confirm its health.

2. 2

   Inspect all battery terminals, main power cables, and chassis/engine ground straps to ensure they are clean, tight, and free of corrosion.

3. 3

   Verify alternator output is within the correct range (typically 13.8V to 14.2V) with the engine running at working RPM.

4. 4

   Visually inspect the main vehicle CAN bus harness for physical damage such as pinching, chafing, heat damage, or rodent damage.

5. 5

   Check the main connectors for each ECU on the network for moisture intrusion, corrosion, or backed-out/damaged pins.

6. 6

   Measure CAN bus resistance with power off and battery disconnected (expected: ~60 Ohms). ~120 Ohms indicates a missing terminating resistor; near 0 Ohms indicates a short circuit; infinite/OL indicates an open circuit.

7. 7

   Measure CAN bus voltage with power on and engine off (expected: CAN High ~2.5V to 3.0V, CAN Low ~2.0V to 2.5V).

1. 1

   Address basic electrical issues

   If voltage or grounding issues were found during preliminary checks, clean terminals, tighten grounds, and replace a faulty battery or alternator. Clear codes and re-test.

2. 2

   Repair wiring and connector faults

   If the resistance check indicates a short or open circuit, use a wiring diagram to isolate sections of the harness (e.g., using the split-half method). Repair damaged wires using environmentally sealed splices or replace corroded connector pins. Avoid soldering if possible.

3. 3

   Address termination resistor issues

   If the resistance check shows 120 Ohms, a terminating resistor is missing. Ensure connectors to the ECUs containing the resistors (typically the Engine ECU and an opposite end module) are secure. If the fault persists, the ECU containing the missing resistor may have an internal failure.

4. 4

   Isolate and replace faulty ECU

   If wiring, power, and termination resistance are correct, disconnect modules from the CAN bus one at a time. When the faulty module is disconnected, network communication should restore. Repair or replace the identified faulty ECU.