Massey Ferguson E3363.03 – Engine ECU: DEF Tank Heater Solenoid Valve High Voltage (ECU) / DEF tank heater coolant valve solenoid short circuit to HIGH SOURCE.

The AGCO SISU POWER Electronic Engine Management (EEM4) monitoring system has detected a short circuit to a high voltage source on the DEF (Diesel Exhaust Fluid) tank heater coolant valve solenoid circuit. This typically means the ECU is seeing higher voltage than expected on this circuit, which prevents the DEF tank heater from operating correctly.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 5608
• MF 5609
• MF 5610
• MF 5611
• MF 5612
• MF 5613
• MF 7614
• MF 7615
• MF 7616
• MF 7618
• MF 7619
• MF 7620
• MF 7622
• MF 7624
• MF 7626

1. 1

   Inspect the wiring harness running from the Engine ECU to the DEF tank heater coolant valve solenoid for chafed wires that may be shorting to a power source.

2. 2

   Disconnect the solenoid valve and inspect the pins for corrosion, moisture, or damage.

3. 3

   Check the operation by temporarily swapping in a known-good dosing/coolant valve to see if the valve itself is the defective component.

4. 4

   Using a multimeter, check the signal wire at the solenoid connector for a short to battery voltage (High Source) while the key is ON.

1. 1

   Power Down

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

2. 2

   Locate the Valve

   Locate the DEF tank heater coolant valve solenoid (usually situated near the DEF tank or along the coolant lines routing to the DEF tank).

3. 3

   Wiring Repair (If Applicable)

   If your diagnostic multimeter tests revealed a short to power in the harness, trace the wire back to the ECU, locate the short, and repair the damaged section of the wiring harness using weather-sealed connectors.

4. 4

   Replace the Solenoid (If Applicable)

   If the wiring tests good, the internal coil of the solenoid is likely shorted. Pinch off the coolant lines leading to the valve to prevent coolant loss. Disconnect the electrical connector. Remove the retaining hardware and detach the coolant hoses from the valve. Install the new DEF tank heater coolant valve solenoid and reattach the hoses.

5. 5

   Reassembly & Clearing Codes

   Reconnect the electrical connector and the battery. Top off any lost engine coolant. Use a diagnostic service tool to clear the active E3363.03 / SPN 3363 FMI 3 fault code from the Engine ECU.

6. 6

   Validation

   Start the engine and monitor the ECU to ensure the fault code does not return to an active state.