New Holland ENG 3047 – Engine Control Module (ECM / Engine ECU): Main Relay 2 Failure _Short circuit to Battery

This code indicates that the engine controller has detected a short circuit to battery voltage (a "high" state) on the circuit responsible for Main Relay 2. This means voltage is present on the relay's control or load circuit when the system expects it to be grounded or off, usually pointing to a wiring issue or a failed relay stuck in a closed/shorted state.

• T7 Series (T7.220, T7.235, T7.250, T7.260, T7.270)
• T8 Series
• T6000 Series (T6010 through T6070)
• B110B Tractor Loader Backhoes
• Case 580 Super N Backhoes

1. 1

   Perform a relay swap test by swapping Main Relay 2 with a known good relay of the exact same type to see if the code clears.

2. 2

   Remove the relay and inspect the socket terminals for melted plastic, corrosion, or bridged pins that could feed 12V power to the control circuit.

3. 3

   Using a multimeter, check the wiring harness between the Engine ECM and the relay block, testing the ground and signal wires for continuity to the battery positive terminal.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent accidental shorts during repair.

2. 2

   Access the Relay Panel

   Open the main electrical distribution box (location varies by model; often in the cab console or under the hood).

3. 3

   Test/Replace the Relay

   Pull Main Relay 2. If the diagnostic swap test proved the relay was faulty, discard it and install a new OEM relay.

4. 4

   Repair the Harness (If Applicable)

   If the relay is good but the circuit is shorted, trace the wiring harness from the relay box back to the Engine ECM. Carefully open the wire loom in areas where the harness bends tightly or rubs against the engine block/chassis.

5. 5

   Fix the Short

   Isolate the chafed wire that is shorting to power. Cut out the damaged section, solder in a new piece of wire of the same gauge, and seal it with heat-shrink tubing.

6. 6

   Reassemble and Clear Codes

   Re-loom the harness, plug the relay back in, and reconnect the battery. Turn the key to the ON position and use a diagnostic tool (or the machine's onboard display) to clear the inactive ENG 3047 code. Start the engine to verify the code does not return.