John Deere 000190.19 – CSC: Engine Speed CAN Signal Too Low

The Cab Suspension Controller (CSC) has detected that the engine speed signal sent over the CAN bus from the Engine Control Unit (ECU) is missing, invalid, or below the expected operational threshold. The CSC requires this engine speed data to properly manage the cab suspension system, as some of its functions are dependent on the tractor's speed.

• 8R Series
• 8RT Series
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R

1. 1

   Restart the tractor to verify if the code reappears, as temporary communication errors can sometimes be cleared by a system reset

2. 2

   Check for any other active fault codes in the CSC, ECU, or other control units that could indicate power supply issues or other CAN bus errors

3. 3

   Use the tractor's diagnostic display to check CAN bus health, looking for high error counts (Passive, Warn, Off) or bus utilization over 45%

4. 4

   Visually inspect the CAN bus wiring harness (yellow and green twisted pair) between the ECU and the CSC for chafing, corrosion, pinch points, or loose connectors

5. 5

   Measure the resistance between the CAN High and CAN Low wires; it should be approximately 60 Ohms (a reading of 120 Ohms indicates a faulty or missing terminating resistor)

1. 1

   Perform diagnostic checks

   Perform all diagnostic checks listed above before proceeding with repairs.

2. 2

   Test CAN bus wiring

   If visual inspection reveals no issues, test the continuity of the CAN High and CAN Low wires between the CSC and the ECU. Check for shorts between the CAN wires, or shorts to power or ground. Verify voltage on CAN High is around 2.6V and CAN Low is around 2.4V.

3. 3

   Isolate CAN bus components

   If wiring is confirmed good, disconnect other controllers from the CAN bus one at a time to see if the fault clears. This helps identify if another faulty controller is disrupting network communication.

4. 4

   Check power and ground

   Verify that both the Engine Control Unit (ECU) and the Cab Suspension Controller (CSC) have a clean, stable power supply and a solid ground connection.

5. 5

   Replace faulty components

   If diagnostics point to a specific failure, replace the faulty part. Replace the terminating resistor if resistance readings were incorrect. If the ECU is not broadcasting the message despite good connections, or if the CSC is determined to be the source, replace the respective control unit.