John Deere 2850.05 – CRU or JDL / JL2: Low Current in Radio Antenna Circuit Detected / Cellular Antenna Error - Open Circuit

The control software triggers this code when the radio or cellular antenna circuit registers a current draw that is too low. This indicates the presence of an open circuit, meaning there is a physical break, a severed wire, or a disconnected plug somewhere between the control module and the antenna.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 6100D-6140D
• 9470RT
• 9520RT
• 9570RT
• M4030
• M4040
• 540G-III
• 548G-III
• 540H
• 548H
• 640
• 648G-III
• 460D
• 7180
• 7280
• 7380
• 7480
• 7580
• 7780
• 7980
• 210K EP

1. 1

   Locate the CRU or JDLink MTG module and check that the antenna cable is firmly plugged into the module

2. 2

   Trace the antenna cable from the module to the exterior roof mount, looking for pinch points, severed wires, or damage caused by debris

3. 3

   Disconnect the antenna cable and inspect the connector pins for moisture intrusion, rust, or corrosion

4. 4

   Use a digital multimeter to test the continuity of the antenna coaxial cable to determine if the wire is broken or the internal circuitry of the antenna base has failed

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground to prevent shorting any sensitive telematics equipment.

2. 2

   Access the Module

   Remove the necessary cab interior panels (headliner or C-pillar cover) to access the CRU or JDLink MTG module.

3. 3

   Disconnect

   Unplug the faulty antenna cable from the module.

4. 4

   Remove the Antenna

   On the exterior of the cab roof, unbolt the antenna base. Carefully pull the old antenna wiring harness out through the cab feedthrough hole.

5. 5

   Install the New Antenna

   Route the new antenna cable through the feedthrough hole. OEM Installation Note: Do not bend the antenna wires too sharply during routing, as this can break the internal coaxial core and immediately cause another open circuit.

6. 6

   Seal the Cab

   Apply silicone paste or a rubber grommet to the feedthrough flange to ensure the cab remains weather-tight and pressurized.

7. 7

   Reconnect and Clear Codes

   Plug the new antenna into the module, restore battery power, and use the CommandCenter display or Service ADVISOR tool to clear the 002850.05 fault code. Verify that the radio/JDLink cellular signal is restored.