Case IH 3879 (F-3507-03) - ECU – Engine Control Module (ECM) / ECU: ECM 12/24 volt actuator supply 3 is shorted to battery voltage.

The engine control module has detected a short to power (battery voltage) on its internal actuator supply circuit #3. This specific power supply circuit outputs through pins 5.06, 5.09, and 6.25 on the ECU connector.

• VESTRUM CVX
• Magnum
• Maxxum
• Optum
• Puma
• Steiger
• Steiger Quadtrac
• Vestrum
• Axial-Flow Combines
• Austoft 9900 sugarcane harvesters
• Graders
• Wheel Loaders
• Farmlift telehandlers

1. 1

   Verify the circuit by focusing diagnostics exclusively on the wiring and components connected to MD1CE101 pins 5.06, 5.09, and 6.25.

2. 2

   Inspect the engine wiring harness for visible signs of chafing, melted insulation, or pinch points where the wires for supply 3 might be rubbing against a 12V/24V power source or the battery positive cable.

3. 3

   Disconnect the harness from the ECU and use a digital multimeter to check for continuity to battery voltage on pins 5.06, 5.09, and 6.25 of the harness connector.

4. 4

   If a short to voltage is present in the harness, disconnect the actuators powered by supply 3 one at a time. If the short to voltage disappears upon unplugging a specific actuator, that component has an internal short.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical damage during testing.

2. 2

   Disconnect ECU

   Locate the Bosch MD1CE101 ECU on the engine block and carefully disconnect the main wiring harness connectors.

3. 3

   Trace the Short

   Based on the multimeter tests performed in the diagnostic phase, trace the wires from pins 5.06, 5.09, and 6.25 to their respective actuators.

4. 4

   Repair Wiring/Actuator

   If the wiring harness is damaged and shorting to a power wire, repair the damaged section using OEM-approved wiring repair techniques (soldering and heat shrink) or replace the affected harness section. If an actuator was found to be internally shorted to power, replace the faulty actuator.

5. 5

   Check ECU Integrity

   If the wiring harness and all actuators test perfectly fine, the short to battery voltage may be internal to the Bosch MD1CE101 ECU itself. In this case, the ECU will need to be replaced or sent out for bench repair.

6. 6

   Reassembly and Clearing

   Reconnect all actuators and the ECU. Reconnect the battery. Connect the CNH Electronic Service Tool (EST) to the diagnostic port, clear the inactive 3879 (F-3507-03) fault code, and run the engine to verify the code does not return.