New Holland ENG 3959 – Engine Control Unit (ECU): COM2 Output Short to Battery TWV2or4 Output Short to Battery

The Engine Control Unit has detected that the common circuit (COM2) supplying voltage/ground to the Two-Way Valve (TWV) solenoids inside the fuel injectors for bank 2 (typically injectors 2 and 4, or 2 and 3 depending on the engine configuration) is shorted to battery voltage.

• L213
• L215
• L218
• L220
• L140
• L150
• L175
• C175

1. 1

   Visually inspect the engine wiring harness and connectors from the ECU to the fuel injectors for damage, corrosion, abrasion, or incorrect attachment.

2. 2

   Disconnect the wiring harness from the ECU and test the injector harness specifically for a short to a high source (battery voltage).

3. 3

   If the wiring harness tests good, isolate the components to check for an internal short within the fuel injector itself (Injector 2, 3, or 4 depending on the specific engine's COM2 bank).

1. 1

   Disconnect battery

   Disconnect the battery before performing electrical repairs.

2. 2

   Repair or replace wiring harness

   If the diagnostic tests reveal a short in the wiring harness, locate the damaged conductor and repair the wiring, or replace the engine wiring harness entirely.

3. 3

   Replace fuel injector(s)

   If the wiring harness is intact and tests perfectly, replace the faulty fuel injector(s) on the affected COM2 bank.

4. 4

   Reconnect components

   Reconnect all harnesses and the battery.

5. 5

   Clear fault codes

   Use a diagnostic service tool or DTC eraser to clear the fault codes from the engine ECU so the machine can resume normal operation without derating.

6. 6

   Verify repair

   Operate the machine while monitoring the display to ensure the error has been resolved.