New Holland ENG 3268 – ENGINE Controller: Main relay 3 - Short circuit to Ground

The Engine Control Unit (ECU) has detected that the voltage on the output circuit of Main Relay 3 (which typically supplies power to the fuel filter heater) has been pulled to ground. This indicates that electrical current is bypassing the intended load and flowing directly into the chassis/ground, usually due to a bare wire touching metal or an internally shorted component.

• T7 Series
• T8.xxx Series
• L218
• L220
• L230
• C238

1. 1

   Locate Main Relay 3 (Fuel Filter Heater Relay) in the main fuse/relay distribution box or chassis harness

2. 2

   Inspect the wiring harness running from the Engine ECU to Main Relay 3, and from the relay to the Fuel Filter Heater for chafed insulation, pinched wires, or melted loom touching the engine block or frame

3. 3

   Swap Main Relay 3 with a known good relay of the exact same type (e.g., a work light or horn relay) to rule out an internal short within the relay itself

4. 4

   Disconnect the electrical connector at the fuel filter heater and check for continuity to ground on the power supply wire. If the short disappears when unplugged, the heater element is internally shorted. If it remains, the wiring harness is shorted to the chassis

5. 5

   Check the Engine ECU connectors for water intrusion, corrosion, or bent pins that could be bridging circuits to ground

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Isolate the Fault

   Based on the diagnostic checks, determine if the fault lies in the relay, the wiring harness, or the fuel filter heater element.

3. 3

   Replace Relay

   If the relay is faulty, replace Main Relay 3 with a new OEM relay. Check the relay socket for melted plastic or spread terminals; repair the socket if heat damage is present.

4. 4

   Repair Wiring

   If the wiring is shorted, trace the shorted wire back from the fuel filter heater to the relay panel. Cut out the damaged section of the wire and solder/heat-shrink a new section of wire of the same gauge. Secure the harness away from sharp metal edges or high-heat sources using zip ties and protective loom.

5. 5

   Replace Fuel Filter Heater

   If the fuel filter heater is faulty, remove the fuel filter. Unthread the faulty heater element/bowl from the filter housing. Install the new fuel filter heater element, ensuring the O-rings are properly seated and lubricated with clean diesel fuel. Reinstall the fuel filter and prime the fuel system.

6. 6

   Clear Codes

   Reconnect the negative battery cable. Turn the ignition key to the ON position. Use a CNH Electronic Service Tool (EST) or a compatible diagnostic scanner to clear the inactive fault codes from the Engine ECU.

7. 7

   Verify Repair

   Start the engine and let it idle. Verify that the ENG 3268 code does not return and that the fuel filter heater is receiving proper voltage.