John Deere 520542.03 – VLC / CSC / CCU: Vehicle CAN Bus High Circuit Voltage High

The voltage on the CAN High circuit is out of range high, indicating that the CAN High wire has shorted to a 12-volt power source, either within the wiring harness or internally inside one of the connected control modules.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6110M-6195M
• 6110R-6215R
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9470RT
• 9520RT
• 9570RT
• 210K / 210L EP Tractor Loaders
• 310K Backhoe Loaders

1. 1

   Perform the 60-Ohm Test: Disconnect the machine's battery and measure the resistance between pins C and D (CAN High and CAN Low) on the 9-pin diagnostic connector. A healthy CAN bus will read exactly 60 ohms. 120 ohms indicates a missing/damaged terminating resistor; OL indicates both are damaged or the bus is severed.

2. 2

   Check for Short to Power: With the battery reconnected and the key ON (engine OFF), use a multimeter to check the voltage on the CAN High pin. A steady 12V indicates a hard short to power.

3. 3

   Perform Module Isolation (The 'Unplug' Method): Disconnect modules one by one (start with VLC, then CSC, CCU, AIC, etc.). If unplugging a specific module causes the CAN High voltage to drop back to normal, that module has an internal short.

4. 4

   Inspect Harness: If unplugging modules does not clear the 12V short, inspect the wiring harness for pinched or chafed wires contacting a 12V power wire. Focus on high-vibration areas, cab roof pass-throughs, and rear chassis routing.

1. 1

   Disconnect Power

   Turn the key switch OFF and disconnect the negative battery cable to prevent further electrical damage.

2. 2

   Repair the Wiring Harness

   If a short is found in the wiring, locate the chafed section where the CAN High wire is contacting a 12V source. Cut out the damaged section, splice in new wire of the same gauge, solder the connection, and seal it with marine-grade heat shrink. Wrap the repaired section in high-temperature cloth tape or split loom.

3. 3

   Replace the Terminating Resistor

   If the 60-ohm test failed, locate the faulty CAN bus terminator (usually located at the physical ends of the harness) and plug in a new resistor.

4. 4

   Replace the Faulty Module

   If the isolation test failed and the VLC or CSC was internally shorted, unbolt the module, disconnect the harness plugs, and install the new OEM module. Note: New control modules will require calibration and software flashing via John Deere Service ADVISOR.

5. 5

   Clear Codes

   Reconnect the battery, turn the key ON, and navigate to the CommandCenter/display diagnostics menu to verify the code has moved from 'Active' to 'Stored'. Clear the stored codes.