John Deere 2006.09 – Engine Control Unit (ECU): Incorrect CAN Bus Message, Information from EIC Control Software

Communication failure on the CAN bus network indicating the Engine Control Unit is receiving intermittent or no messages from the Electronic Instrument Cluster (EIC) or Primary Display Unit (PDU).

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8R/8RT Series (8245R to 8400R)
• 6M Series (6170M)
• 5E Series (5045E)
• 6000 Premium Series (6230, 6330, 6430)
• John Deere 3029
• John Deere 4045
• John Deere 6090
• 9.0L OEM diesel engines

1. 1

   Cycle the power by restarting the tractor to see if the code clears or moves from Active to Stored (transient glitch)

2. 2

   Check battery voltage and ensure terminals are clean, as low system voltage can cause CAN bus communication drops

3. 3

   Inspect connectors at the Engine Controller (ECU) and the Display (EIC/PDU), including the interconnect between the two wiring harnesses

4. 4

   Test CAN bus resistance at the diagnostic port with key off and battery disconnected (60 ohms is healthy; 120 ohms indicates a failed resistor or broken wire; 40 ohms or lower indicates a short)

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Clean and Reseat Connections

   Disconnect the main harness connectors at the ECU and the EIC/Display. Inspect for pushed pins, corrosion, or moisture. Clean with contact cleaner, apply dielectric grease, and firmly reseat them.

3. 3

   Trace the Harness

   Physically inspect the wiring harness running from the engine compartment to the cab. Look for pinch points, chafing, or melted wires, particularly where the harness crosses metal brackets. Repair any broken wires using proper solder and heat-shrink tubing.

4. 4

   Replace Terminating Resistor

   If your multimeter test yielded 120 ohms, locate the CAN bus terminating resistors (usually one near the ECU and one near the display/cab). Unplug the suspect resistor and test it directly (it should read 120 ohms on its own). Replace it if it reads open or out of spec.

5. 5

   Isolate Modules (If Shorted)

   If the bus resistance is too low (e.g., 40 ohms), disconnect modules on the CAN network one by one until the resistance returns to 60 ohms. The last module unplugged is the shorted component and will need replacement.

6. 6

   Clear Codes

   Reconnect the battery, turn the key on, and use a diagnostic tool to clear the inactive codes.