John Deere 000190.19 – CCU: Missing Engine Speed CAN Message

The system has detected a missing CAN BUS message on the Powertrain CAN bus, specifically from the Engine Module regarding engine speed. This indicates a communication breakdown between the Engine Control Unit (ECU) and the Chassis Control Unit (CCU/CSC), meaning the chassis controller is not receiving the expected engine speed data required for its functions.

• 6130
• 6930
• 6700
• 7200
• 7210
• 7400
• 7410
• 7510
• 7600
• 7610
• 7700
• 7710
• 7800
• 7810

1. 1

   Visually inspect the wiring harness and connectors between the Engine Control Unit (ECU) and the Chassis Control Unit (CCU) for chafed wires, broken wires, loose pins, corrosion, or damage from heat or moisture. Note: CAN High is typically Yellow, and CAN Low is Green.

2. 2

   Check for other active or stored fault codes that could indicate a widespread electrical issue, such as low battery voltage or faults in other control units.

3. 3

   Verify CAN Bus resistance with the machine's power off and battery disconnected. A healthy bus reads approximately 60 Ohms. A reading of 120 Ohms indicates an open circuit or missing terminator, while significantly lower indicates a short between CAN lines.

4. 4

   Check for shorts to power or ground. With power on, CAN High and Low should be at approximately 2.5 volts. With power off, there should be no continuity between either CAN line and ground.

5. 5

   Inspect and clean all major ground connections for the control modules and the main chassis.

1. 1

   Isolate faulty component

   If initial checks point to a CAN bus problem, disconnect controllers from the CAN bus one at a time while monitoring the resistance or signal to isolate the source of the fault.

2. 2

   Repair wiring and connectors

   Repair any damaged sections of the wiring harness. Clean corroded connector pins and apply dielectric grease. Replace any severely damaged connectors.

3. 3

   Replace terminating resistor

   If a terminating resistor is determined to be faulty (e.g., network resistance is 120 Ohms), replace the integrated controller or separate harness plug containing the terminator.

4. 4

   Replace control module

   If all wiring and terminators are good, replace the Engine Control Unit (ECU) or Chassis Control Unit (CCU) if one is flooding the network with bad data or has an internal open circuit. This is a last resort.

5. 5

   Clear codes and test

   After repairs are completed, clear all fault codes and operate the machine to ensure the communication issue is resolved.