New Holland ENG 3961 – ENGINE ECU: COM2 Output Open Load Both TWV2 and TWV4 Open Load

The Engine Control Unit (ECU) has detected an open circuit (open load) on the COM2 output circuit. This means the electrical circuit supplying power or ground to specific injectors (TWV2 and TWV4, typically Injectors 2 and 4) is broken or disconnected.

• L218
• L220
• C227
• SR175
• B90B
• B100B
• T4 series
• T5 series
• Workmaster series

1. 1

   Inspect the wiring harness between the Engine ECU and fuel injectors 2 and 4 for broken wires, chafing, or disconnected connectors.

2. 2

   Check the ECU connector pins and the injector connectors for corrosion, moisture, or poor contact.

3. 3

   Disconnect the harness from injectors 2 and 4 and measure the resistance of the injector coils (TWV2 and TWV4) using a multimeter. An infinite resistance reading indicates an open circuit inside the injector solenoid.

4. 4

   If the injectors test good, check the continuity of the wiring harness from the ECU connector (COM2 pins) to the injector connectors to locate the break in the wire.

1. 1

   Safety First

   Turn off the machine, remove the key, and wait at least 30 seconds for the ECU to power down. Disconnect the battery ground cable.

2. 2

   Access the Injectors

   Remove any engine covers or valve cover components necessary to access the fuel injectors and their wiring harness.

3. 3

   Test and Isolate

   Disconnect the wiring harness connectors from the affected injectors (Injectors 2 and 4). Measure the resistance across the terminals of each injector.

4. 4

   Replace Faulty Component

   If an injector shows an open circuit (infinite resistance), replace the faulty fuel injector. If the injectors test within specification, repair or replace the damaged section of the injector wiring harness.

5. 5

   Reassembly

   Reconnect the injector harness and the battery ground cable.

6. 6

   Clear and Verify

   Connect a diagnostic tool to clear the ENG 3961 fault code. Start the engine and verify that the code does not return and the engine runs smoothly without misfires.