John Deere 520543.04 – AIC (Armrest Interface Control Unit): Vehicle CAN Bus Circuit Voltage Low

The voltage on the CAN- (CAN Low) wire has dropped below acceptable operating parameters, which typically suggests a short to ground within the CAN bus circuit.

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

1. 1

   Switch the ignition OFF and then ON again to perform a system reboot and rule out a temporary software glitch.

2. 2

   Visually inspect the AIC (Armrest/Cab Module) for physical damage, loose connections, or corrosion at the harness connectors.

3. 3

   Test the CAN bus electrical circuit (specifically the CAN- lead) using a multimeter to check for continuity and verify if there is a short to ground.

4. 4

   Disconnect the AIC module to isolate it. If the CAN bus voltage returns to normal on the rest of the network, the internal circuitry of the AIC is shorted. If the voltage remains low, the short is in the wiring harness.

1. 1

   Disconnect Power

   Always disconnect the battery before servicing electrical modules or repairing wiring.

2. 2

   Repair Wiring

   If the diagnostic tests revealed a short to ground or damaged wiring on the CAN- lead, repair or replace the affected section of the wiring harness. Ensure all pins in the connectors are seated securely and free of corrosion.

3. 3

   Replace the Module

   If the wiring harness is intact but the AIC module is internally shorted (causing the voltage drop), remove the defective Armrest Interface Control Unit and install a replacement.

4. 4

   Update Software

   Ensure that the control software/firmware for the new module (or existing module, if wiring was the issue) is updated to the latest version to prevent internal EEPROM read errors.

5. 5

   System Reset and Test

   Reconnect power, turn the key ON, and perform operational tests to verify that the CAN bus communication is restored and the fault code does not return.