Massey Ferguson 3361.03 – Engine Control Unit (ECU) / EEM4: DEF Injector Voltage Issue

The control module has detected that the voltage on the low-side control circuit of the Diesel Exhaust Fluid (DEF) dosing injector is out of range high, indicating a short circuit to a 12V power source.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 7700 Series

1. 1

   Inspect the wiring harness running from the Engine ECU to the DEF Dosing Valve on the exhaust for chafing, melted insulation, or pinched wires that could cause a short to a 12V power wire.

2. 2

   Disconnect the DEF injector and the ECU connector, then use a digital multimeter to check for continuity to power (12V) on the low-side control wire of the DEF injector circuit.

3. 3

   Measure the internal resistance of the DEF injector to determine if the injector itself is internally shorted to its own power supply.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Access the Injector

   Locate the DEF Dosing Valve (Injector) mounted on the exhaust SCR system.

3. 3

   Disconnect Lines

   Unplug the electrical connector. Carefully disconnect the DEF fluid line from the injector. (Note: Clean up any spilled DEF fluid immediately with warm water, as it is highly corrosive to metal and wiring).

4. 4

   Address the Short

   If the diagnostic tests proved the wiring harness is shorted, locate the damaged section, repair the wire, and seal it with heat-shrink tubing. If the DEF injector is internally shorted, proceed to replace it.

5. 5

   Remove the Injector

   Unbolt the faulty DEF injector from the exhaust pipe mounting flange.

6. 6

   Clean and Prep

   Clean the mounting surface on the exhaust pipe to ensure a proper seal.

7. 7

   Install New Part

   Install the new DEF injector using a new gasket/seal. Torque the mounting bolts to OEM specifications.

8. 8

   Reconnect

   Reconnect the DEF fluid line and the electrical connector.

9. 9

   Restore Power

   Reconnect the battery.

10. 10

    Clear and Verify

    Use a diagnostic scan tool to clear the 003361.03 fault code. Perform a forced stationary regeneration or a DEF system dosing test via the diagnostic tool to verify the repair and ensure there are no fluid or exhaust leaks.