Case IH 520205-04 - PCM – PCM: Internal Backup Battery Voltage Above Normal

The PCM's internal backup battery voltage is above normal or shorted to a high source.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect 240
• Case IH Magnum AFS Connect 280
• Case IH Magnum AFS Connect 400

1. 1

   Verify the exact code and description on the tractor's display.

2. 2

   If diagnosing the Internal Battery (520205-04): Check the main power supply and ground circuits to the PCM. If the module is receiving proper external voltage but still logging an internal battery fault, the lithium-ion backup battery inside the PCM is likely failing or depleted.

3. 3

   If diagnosing the CAN Communication (520368-02): Inspect the CAN bus wiring (CAN-1, CAN-2) leading to the PCM. Check for open circuits, verify the health of the terminating resistors (the CAN network should read approximately 60 ohms with the battery disconnected), and ensure the PCM connectors are free of corrosion or pushed-out pins.

1. 1

   Verify the Fault

   Access the diagnostic menu on the AFS Pro display to confirm whether you are chasing a CAN network error or an internal battery voltage error.

2. 2

   Inspect Wiring

   Locate the PCM and disconnect its main harness. Inspect the pins for moisture, corrosion, or damage.

3. 3

   Test Power/Ground

   Use a multimeter to verify that the PCM is receiving steady battery voltage and has a clean ground.

4. 4

   Replace the Internal Battery (For 520205)

   If external power is good, the PCM's internal lithium-ion backup battery must be replaced. Remove the battery cover on the PCM, swap the battery, and clear the codes.

5. 5

   Replace the PCM (If necessary)

   If replacing the internal battery or repairing the CAN wiring does not resolve the respective faults, the PCM itself has suffered an internal hardware failure. Replace the PCM and have a dealer flash/reprogram the new module to the tractor.