Case IH 12873 – CCM (Central Control Module / Chassis Control Module): System Undervoltage (TRM30)

The control module is detecting an input voltage that is too low (undervoltage) on its direct battery power supply circuit (Terminal 30 / KL30).

• MAXXUM T4E
• Stage V Mid-Range (MR) tractors
• Farmall series (40, 45, 50, 115U Efficient Power)
• Maxxum series
• Puma series

1. 1

   Measure battery voltage directly at the terminals (should be ~12.6V resting and ~14V running). A weak battery or failing alternator will cause system-wide undervoltage.

2. 2

   Check voltage at the TRM30 input pin on the CCM connector using a multimeter. The voltage must match battery voltage; lower voltage indicates high resistance.

3. 3

   Inspect main power fuses and Terminal 30 power relays in the fuse box for blown fuses, melted plastic, or corroded relay contacts.

4. 4

   Check Terminal 31 (KL31) ground pins on the module and trace them to chassis ground points to ensure they are clean and tight.

5. 5

   Inspect the wiring harness between the battery, fuse box, and the CCM for chafing, breaks, or corrosion.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent accidental shorts during repair.

2. 2

   Access the CCM

   Locate the Central Control Module and disconnect its main wiring harness.

3. 3

   Repair Wiring/Connections

   If the diagnostic checks revealed a voltage drop between the battery and the CCM, trace the TRM30 wire. Repair any broken wires, clean corroded connectors with contact cleaner, and replace damaged pins.

4. 4

   Replace Faulty Relays/Fuses

   If a Terminal 30 relay is sticking or has high internal resistance, replace it with a new OEM relay. Replace any blown fuses.

5. 5

   Clean Grounds

   Unbolt the main chassis grounds and the CCM specific grounds. Wire-brush the ring terminals and the chassis contact point until bare metal is exposed, then reattach securely.

6. 6

   Re-test Voltage

   Reconnect the battery and measure the voltage at the CCM connector again to verify the voltage drop has been eliminated.

7. 7

   Module Replacement (Worst Case)

   If the wiring, relays, and battery all test perfectly but the CCM still logs an internal TRM30 undervoltage fault, the module itself has suffered an internal hardware failure and must be replaced and reprogrammed by a dealer.

8. 8

   Clear Codes

   Reconnect the module, turn on the ignition, and use a diagnostic scan tool to clear the 12873 fault code.