John Deere 523774.04 – VTi: Voltage Is Too Low

The system has detected that the voltage on the CAN (Controller Area Network) Low line is below the acceptable operating range. In a resting state, the CAN Low wire should have approximately 2.5V, but this fault triggers when it drops significantly below that threshold (typically under 2.0V). This voltage drop indicates a communication network anomaly that may affect the proper operation and data transmission of connected components, such as StarFire GPS receivers and other electronic control units.

• 6M Series
• 6R Series
• 7R Series
• 8R Series
• 9R Series
• 770G
• 772G
• 6230 Premium
• 6430 Premium
• Combines
• Equipment using StarFire or GreenStar systems

1. 1

   Visually inspect the CAN bus wiring harness for chafing, cuts, pinched wires, or corrosion, focusing especially on the StarFire receiver and ISOBUS breakaway connectors.

2. 2

   Inspect all related connectors (including the main rear ISOBUS and receiver connectors) for cleanliness and corrosion. Perform a light pull test on the wires to identify loose pins.

3. 3

   Check the active and passive 120-ohm terminating resistors on the CAN bus network, as a faulty or missing terminator can cause communication errors.

4. 4

   With the ignition off, measure resistance between the CAN High (yellow wire) and CAN Low (green wire) pins at a diagnostic connector. A healthy CAN bus should read approximately 60 ohms.

5. 5

   With the ignition on, measure the DC voltage of the CAN lines to a good chassis ground. CAN Low should be 2.0V to 2.5V, and CAN High should be 2.5V to 3.0V.

1. 1

   Rectify simple connection issues

   Clean, repair, or replace any loose connectors, corroded pins, or visibly damaged wires found during the initial visual inspection.

2. 2

   Isolate the fault

   Unplug components from the CAN bus one at a time (such as the StarFire receiver) and re-check if the fault code disappears. This helps determine if the issue lies within a specific component or the main harness.

3. 3

   Test and replace terminating resistors

   Swap the active and passive terminators to see if the problem changes or resolves. If swapping them moves or fixes the problem, replace the faulty terminator.

4. 4

   Repair or replace wiring harness

   If a specific section of the wiring harness is faulty, solder and properly seal the damaged wires to prevent future corrosion. If the harness is extensively damaged, replace it entirely.

5. 5

   Program control unit

   If all physical wiring and components are verified as good and the fault persists, the Advanced Display Unit (ADU) or another control unit may need to be reprogrammed as a final step.