John Deere 520542.03 – TEC / AIC / OIC: Vehicle CAN Bus Circuit Voltage High

The voltage on the CAN+ (CAN High) circuit is excessively high, which strongly suggests a short to a 12-volt power source (battery voltage) somewhere on the CAN Bus network.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8310RT
• 8335RT
• 8360RT
• 210K EP Tractor Loader
• 210L EP Tractor
• 310K Backhoe Loader

1. 1

   With Key Switch OFF and Engine OFF, inspect the physical condition of the CAN bus wiring harness leading to the TEC, AIC, or OIC module for chafing, pinched wires, or exposed copper.

2. 2

   With Key Switch ON, use a multimeter to measure the voltage on the CAN High and CAN Low pins at the module connector.

3. 3

   Disconnect the module (TEC, AIC, or OIC) from the harness to isolate the short. If the 12V short remains on the harness side, the wiring is at fault. If the voltage normalizes on the harness but the module outputs 12V on the CAN pins, the module has an internal short.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent further electrical damage.

2. 2

   Access the Module

   Locate the reporting module (Cab Roof Module, Armrest Console, or Operator Interface Console) based on your machine's cab configuration.

3. 3

   Inspect and Repair Wiring

   If the diagnostic checks revealed a short to 12V in the harness, trace the CAN+ wire from the module back to the main CAN backbone. Repair or splice any damaged sections of the wiring harness where it may be rubbing against the chassis or a 12V power wire.

4. 4

   Replace the Module (If Necessary)

   If the wiring harness tests perfectly and the short is isolated internally to the TEC, AIC, or OIC, unbolt the module, disconnect the harness, and install a replacement unit.

5. 5

   Verify Repair

   Reconnect the battery, turn the key switch to ON, and use a diagnostic tool to clear the 520542.03 fault code. Verify that the CAN bus voltage has returned to normal operating ranges (typically around 2.5V - 2.7V for CAN High) and that the code does not return.