Case IH 3268 – Engine ECU: Engine ECU Fuel Pump Output - Shorted To Low Source

The Engine Control Unit (ECU) has detected that the output circuit responsible for energizing Main Relay 3 (which typically controls the fuel pump or fuel filter heater) has a short circuit to ground (low source).

• skid steer
• Magnum
• Steiger
• Puma
• SSL (Skid Steer Loaders)
• CTL (Compact Track Loaders)

1. 1

   Perform a relay swap test by swapping Main Relay 3 (fuel pump or filter heater relay) with a known good relay of the same type (e.g., horn or work light relay) to check for an internal short.

2. 2

   Visually inspect the wiring harness running from the Engine ECU to the relay panel for chafed insulation, pinched wires, or areas rubbing against the engine block or frame.

3. 3

   Disconnect the Engine ECU and the relay block to inspect the pins for corrosion, moisture ingress, or bent terminals that could be bridging the circuit to a ground pin.

4. 4

   With the battery disconnected and the ECU/relay unplugged, use a multimeter to measure the resistance between the ECU output pin for Relay 3 and a known chassis ground (should read as an open circuit/OL).

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical spikes during the repair.

2. 2

   Isolate the Fault

   Based on the multimeter test, determine if the short is in the relay itself or the wiring harness.

3. 3

   Repair the Wiring

   If the harness is shorted to ground, trace the wire to find the damaged section. Cut out the damaged wire, splice in a new section of the correct gauge, and seal it with marine-grade heat shrink tubing. Secure the harness away from sharp edges or heat sources.

4. 4

   Replace the Relay

   If the wiring tests good but the relay coil is internally shorted, install a new OEM replacement relay into the Main Relay 3 slot.

5. 5

   Reassemble and Clear Codes

   Reconnect the ECU, relay panel, and battery. Turn the key to the ON position. Use your diagnostic service tool or the machine's Universal Display Plus to clear the inactive fault codes.

6. 6

   Verify Repair

   Start the engine and verify that the fuel pump/heater operates correctly and that fault code 3268 does not return.