New Holland ENG 3960 – Engine ECU (ISM-DI Engine): COM2 Output Short to Ground TWV2or4 Output Short to Ground

The Engine Control Module has detected a short circuit to ground on the injector drive circuit for Bank 2 (COM2). This specific circuit supplies the power/ground to the Two-Way Valves (TWV) for fuel injectors 2 and 4 (TWV2 and TWV4).

• L218
• L220
• SR175
• SV185
• B90B
• B100B

1. 1

   Visually inspect the engine wiring harness routing from the Engine ECU to the fuel injectors for cylinders 2 and 4 for chafed insulation, melted wires, or pinch points

2. 2

   Disconnect electrical connectors at injectors 2 and 4 and measure the resistance of each injector coil to the injector body (ground) to check for an internal short

3. 3

   With the ECU and injectors disconnected, test the COM2 circuit wiring for continuity to ground

4. 4

   Check the Engine ECU connector pins for corrosion, moisture ingress, or bent pins that could bridge the COM2 circuit to a ground pin

1. 1

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

2. 2

   If the diagnostic checks reveal a damaged wiring harness, repair the damaged section using proper soldering and heat-shrink techniques, or replace the injector wiring harness entirely.

3. 3

   If an injector (TWV2 or TWV4) failed the coil test (internally shorted to ground), remove the high-pressure fuel lines and the faulty fuel injector.

4. 4

   Install the new fuel injector with new seals/copper washers.

   Do not mix genuine and aftermarket injectors on the same engine due to atomization differences; replacing the set is often recommended if high hours are present.

5. 5

   Reconnect the fuel lines and electrical connectors.

6. 6

   Reconnect the battery.

7. 7

   Use the New Holland Electronic Service Tool (EST) or a compatible Can-Bus DTC eraser to clear the ENG 3960 fault code from the Engine ECU.

8. 8

   If a new injector was installed, use the EST to write the new injector calibration codes to the ECU.

9. 9

   Prime the fuel system and run the engine to verify the repair and ensure no leaks are present.