John Deere 520965.04 – OIC (Operator Interface Console): CAN BUS Terminating Resistor, CAN BUS Voltage Too Low

The control software detects that the voltage on the CAN BUS is abnormally low, indicating a short circuit to ground on the CAN BUS network.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC

1. 1

   Isolate the Network: Unplug the connector from the OIC device.

2. 2

   Test for Short to Ground: Using a multimeter, measure the resistance between the CAN Hi pin and Chassis Ground, and then between the CAN Low pin and Chassis Ground. Normal reading should be open (Mega ohms). A reading of 10K ohms or less confirms a short to ground.

3. 3

   Test Terminating Resistance: Measure the resistance between the CAN Hi and CAN Low pins. A healthy CAN network with two 120-ohm terminating resistors should read approximately 60 ohms.

4. 4

   Visual Inspection: Inspect the CAN connectors and wiring harness for water intrusion, corrosion, or chafing against the chassis.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent transient current spikes that could damage module transceivers during testing.

2. 2

   Segment the CAN Bus

   Because a short to ground will pull down the entire network, you must isolate the fault. Disconnect junction blocks or modules one by one while monitoring the resistance to ground on the CAN lines.

3. 3

   Locate the Fault

   When the short to ground disappears from your multimeter, the last segment or module you unplugged contains the fault.

4. 4

   Inspect the Terminating Resistors

   Locate the CAN BUS terminating resistors (on 6000-series tractors, these are often located in the roof panel to the right of the operator or behind the instrument panel on the right-hand side of the steering column). Check the resistor and its pigtail for melted insulation or backed-out crimps.

5. 5

   Repair or Replace

   Repair the chafed wiring harness segment, clean out any moisture/corrosion in the connectors, or replace the shorted terminating resistor.

6. 6

   Reassemble and Clear Codes

   Reconnect all modules, restore battery power, and clear the OIC fault codes using your diagnostic tool.