John Deere 002007.09 – RLC, ECU, or VCU: CAN Bus Message Issue RPT to RLC

A communication issue has been detected on the CAN bus indicating an abnormal update rate (FMI 09). Specifically, a data message expected from the RPT (Rear PTO) Transmission Module is not being correctly transmitted or received by the Cab Roof Module (RLC) in a timely manner. The message may be missing entirely or arriving too slowly.

1. 1

   Record all active and inactive fault codes from all vehicle controllers before clearing, as other codes may point to the root cause.

2. 2

   Visually inspect the wiring harness and connectors associated with the RPT and RLC modules for chafing, corrosion, pinched wires, or loose connections, especially in high-vibration areas.

3. 3

   Power cycle the machine (turn key off, wait for complete power down, and restart) to see if a temporary communication glitch resolves.

4. 4

   With machine power OFF, measure resistance between CAN High and CAN Low wires (should be approximately 60 ohms; 120 ohms indicates a missing terminating resistor or open circuit, while significantly lower indicates a short).

5. 5

   With key ON, measure CAN bus voltages to chassis ground (CAN High should be 2.5-3.0 VDC, CAN Low should be 2.0-2.5 VDC).

1. 1

   Isolate faulty component

   If CAN bus resistance or voltage readings are incorrect, unplug modules from the CAN network one at a time. The module that causes readings to return to normal when disconnected is likely the source of the problem.

2. 2

   Repair wiring and connectors

   Clean corroded connector pins and sockets thoroughly and apply dielectric grease. Repair any chafed or broken wires using appropriate splicing and sealing techniques.

3. 3

   Verify module power and ground

   Check that both the RPT and RLC modules have a clean, stable power supply and a solid ground connection to prevent malfunction.

4. 4

   Replace faulty module

   As a last resort, if all wiring and connections are good, replace the RPT or RLC module depending on which is failing to communicate.