New Holland 3268 – ECU: Engine ECU Fuel Pump Output - Shorted To Low

The Engine Control Unit (ECU) has detected an abnormally low voltage or a direct short to ground in the electrical circuit that provides power to the fuel pump. The ECU sends a voltage signal to activate the fuel pump via a relay; this code is triggered when the ECU recognizes that this voltage is being drawn directly to ground, preventing the pump from operating correctly. This indicates an electrical issue in the connection or wiring related to the fuel pump output, rather than a mechanical failure of the pump itself.

• CX720
• CX840
• SSL
• CTL

1. 1

   Verify if the fault code is currently active using a diagnostic service tool and note any other related active codes.

2. 2

   Inspect the fuse and relay associated with the fuel pump circuit (e.g., fuse F-28 and relay K-07 on CX720 models) for blown fuses indicating a short.

3. 3

   Visually inspect the wiring harness from the ECU to the fuel pump relay, and from the relay to the fuel pump, for chafing, melting, abrasion, or corrosion.

4. 4

   Disconnect and inspect electrical connectors at the ECU, fuel pump relay, and fuel pump for corrosion, bent pins, pushed-out pins, or moisture intrusion.

1. 1

   Isolate the circuit

   Disconnect the fuel pump and the fuel pump relay from the electrical harness.

2. 2

   Test for short to ground

   Using a digital multimeter set to measure continuity (Ohms), check for continuity between the fuel pump power supply wire (at the relay socket terminal leading to the pump) and a known good chassis ground. If continuity exists (near 0 Ohms), locate and repair the damaged section of the wire.

3. 3

   Test fuel pump relay circuit

   Check for a short to ground on the wire from the ECU to the fuel pump relay's control coil. If no short is found in the wiring, swap the fuel pump relay with a known good relay of the same type to see if the fault clears.

4. 4

   Test the fuel pump

   With the pump disconnected, measure the resistance between its power terminal and its casing. There should be no continuity. If continuity exists, the pump's internal motor has a short to ground and must be replaced.

5. 5

   Test ECU output

   If all wiring, the relay, and the pump test good, use a diagnostic service tool to test the ECU's output driver for the fuel pump. A faulty ECU is rare and should be considered a last resort.