Case IH 522840-06 - PCM – PCM: Cellular antenna short circuit to ground

The control module has detected that the primary cellular antenna signal circuit (the coaxial cable or the internal antenna element itself) has a resistance value that is lower than expected, indicating that the signal wire is making direct electrical contact with a ground source (such as the machine's chassis or the cable's outer shielding).

• MAGNUM AFS Connect
• Steiger AFS Connect
• Optum AFS Connect
• Puma AFS Connect
• Axial-Flow AFS Connect

1. 1

   Visually inspect the cellular antenna coaxial cable routing from the PCM to the cab roof for pinched wires, chafing against the cab frame, or severe bends.

2. 2

   Perform a cable isolation test by turning off the ignition and disconnecting the coaxial cable from both the PCM and the roof antenna.

3. 3

   Test continuity/resistance using a multimeter between the center pin of the coaxial cable and the outer metal connector housing (ground shield). Low resistance indicates a shorted cable; infinite resistance (OL) indicates the short is internal to the antenna.

4. 4

   Inspect the PCM and antenna connectors for water intrusion, corrosion, or bent pins that could bridge the signal to ground.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery ground to prevent electrical spikes during module handling.

2. 2

   Access the Components

   Locate the PCM (typically located under the cab trim or behind the seat, depending on the specific tractor model) and the cellular antenna mounted on the exterior roof.

3. 3

   Replace the Faulty Component

   If the cable failed the diagnostic test: Route a new OEM coaxial cable from the PCM to the roof mount. Ensure the new cable is secured with zip ties and is not pinched by interior cab panels. If the cable passed the diagnostic test: Unbolt the cellular antenna from the roof mount. Clean the mounting surface, install the replacement cellular antenna, and securely fasten the coaxial connector.

4. 4

   Reassemble and Reconnect

   Reconnect the battery.

5. 5

   Clear Codes

   Turn the ignition on. Access the "Diagnostics" -> "Faults" screen on the AFS Pro 1200 or AFS Pro 700 display to verify the code has changed from "Active" to "Inactive/History". Clear the code.

6. 6

   Verify Operation

   Check the AFS Connect cellular signal strength icon on the display to ensure the modem is successfully communicating with the cellular network.