Case IH 520203-04 - PCM – PCM: Internal backup battery voltage is below normal, or shorted to a low source

The PCM contains an internal lithium-ion backup battery designed to maintain critical memory, telematics, and GPS data when the machine's main power is turned off. This code typically triggers when the battery has reached the end of its service life or if there is a short circuit in the battery's voltage supply line.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Optum
• Puma
• Axial-Flow 250 series
• Axial-Flow 260 series
• 7250
• 8250
• 9250
• 50 Series Patriot sprayers
• Legacy equipment with PCMf modem

1. 1

   Check Module Age: The PCM internal backup battery has a minimum service life of 5 years. If the machine or module is around or past this age, the battery is naturally depleted.

2. 2

   Verify Main Power: Check the machine's main battery voltage and alternator charging system to ensure the PCM is receiving proper primary power, as low system voltage can cause erroneous internal voltage faults.

3. 3

   Inspect Wiring: Inspect the PCM wiring harness and connectors for any signs of damage, corrosion, or a short to ground that could be pulling the voltage down.

1. 1

   Safety First

   Park the machine on a level surface, turn off the engine, remove the key, and disconnect the main battery ground (negative) cable.

2. 2

   Locate the PCM

   Find the Processing and Connectivity Module. Depending on the machine, it is typically mounted on the cab roof (near the antenna array) or inside the cab's electrical compartment.

3. 3

   Access the Battery Compartment

   The PCM is designed with a specific internal battery compartment. If the mounting location does not allow enough clearance to access the compartment door, unbolt the PCM from its mounting bracket.

4. 4

   Replace the Battery

   Open the battery compartment on the PCM, remove the depleted lithium-ion backup battery, and install the new OEM replacement battery.

5. 5

   Reassembly

   Secure the battery compartment cover. Reinstall the PCM and any cab panels or guards that were removed.

6. 6

   Reconnect Power

   Reconnect the main battery ground cable.

7. 7

   System Check

   Power on the machine. Use the AFS Pro display or the Electronic Service Tool (EST) to clear the 520203-04 fault code and confirm that the PCM boots up properly and the code does not return.