Case IH 3878 (F-3508-31) - ECU – Engine Control Module (ECM): ECM 12/24 volt actuator supply 2 is shorted to battery voltage

The Engine Control Module (ECM) monitors the voltage supplied to various engine actuators. When it logs this code, it means it has detected an unexpectedly high voltage (battery voltage) on the actuator supply 2 circuit, specifically on the ECM connector pins 2.08, 4.03, and 4.19. This prevents the actuators on this circuit from functioning correctly and triggers engine protection modes.

• VESTRUM CVX
• Axial-Flow Combine 5140
• Axial-Flow Combine 6140
• Axial-Flow Combine 6150
• Axial-Flow Combine 7140
• Axial-Flow Combine 7150
• Axial-Flow Combine 7250
• Axial-Flow Combine 8250
• Axial-Flow Combine 9240
• Axial-Flow Combine 9250
• Magnum 250
• Magnum 280
• Magnum 310
• Magnum 340
• Magnum 380 CVX
• Optum 250 CVX
• Optum 300 CVX
• Maxxum 115
• Maxxum 135
• Maxxum 150
• Puma X 140
• Puma CVX 150
• Vestrum 130 CVX DRIVE
• Farmlift 737

1. 1

   Visually inspect the wiring harness leading to the Bosch MD1CE101 ECM, specifically looking for chafing, melted insulation, or pinch points where the harness might be shorting to a battery power source.

2. 2

   Disconnect the ECM connector and use a digital multimeter to test pins 2.08, 4.03, and 4.19 on the harness side for voltage. If battery voltage is present with the ECM disconnected, there is a short to power in the wiring harness.

3. 3

   If the wiring harness tests fine, disconnect the actuators on supply 2 one by one while monitoring the circuit voltage. If the short disappears when a specific actuator is unplugged, that component is internally shorted.

4. 4

   If the harness and all actuators are verified to be in good condition and free of shorts, check for an internal failure within the Bosch MD1CE101 ECM itself.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical damage during repairs.

2. 2

   Repair Wiring

   If a short to battery voltage was found in the harness leading to pins 2.08, 4.03, or 4.19, cut out the damaged section of wire and splice in a new section using weather-sealed heat-shrink connectors. Secure the harness away from heat sources and sharp edges.

3. 3

   Replace Faulty Actuator

   If an actuator was found to be internally shorted during the isolation test, unbolt and replace the faulty actuator. Reconnect its electrical connector.

4. 4

   Replace and Reprogram ECM

   If the ECM is internally shorted, remove the mounting bolts and disconnect the harness. Install a replacement Bosch MD1CE101 ECM. A new ECM will require programming/flashing with the Case IH Electronic Service Tool (EST) to match the machine's specific engine dataset and immobilizer parameters.

5. 5

   Clear Codes

   Reconnect the battery. Connect the Case IH EST diagnostic tool, clear the active 3878 (F-3508-31) fault code, and run the engine to verify the code does not return.