New Holland ENG 3744 – Engine Control Unit (ECU) / EDC: EDC - Power stages, Injector: Diagnostic fault check to report the error in over voltage monitoring

The engine controller has detected that the voltage on the internal power stage circuit responsible for firing the fuel injectors has exceeded the maximum allowable threshold.

• L220
• L221
• L223
• L228
• L230
• L234
• C227
• T4 F/N/V
• T4LP
• T4.75
• T4.85
• T5 Dual Command
• T5 Electro Command
• Workmaster series

1. 1

   Test the battery and alternator output while the engine is running to ensure the alternator voltage regulator has not failed (which would overcharge the system and cause an overvoltage spike to the EDC).

2. 2

   Inspect the engine wiring harness between the EDC and the fuel injectors. Look for chafed wires that could be causing a short-to-power (+Ubat) on the injector circuits.

3. 3

   Look for accompanying codes (such as 3762 for Level 2 Over Voltage of Supply, or 3743 for Undervoltage) which can help isolate if the issue is a global machine voltage problem or an isolated internal EDC failure.

1. 1

   Disconnect battery

   Disconnect the machine's battery power.

2. 2

   Disconnect harnesses

   Disconnect the main wiring harnesses from the EDC module.

3. 3

   Remove EDC module

   Remove the faulty EDC module from its mounting bracket.

4. 4

   Install replacement EDC module

   Install the replacement EDC module and reconnect the harnesses (it is recommended to replace the ECU's O-ring seal if applicable).

5. 5

   Program EDC module

   Connect the New Holland Electronic Service Tool (EST) to flash the correct engine dataset, program the injector codes, and restore self-learning parameters.