Case IH F-3363-04 - ECU – Engine Control Unit (ECU) or Dosing Control Unit (DCU) / SCR System Module: DEF/AdBlue tank heater actuator short circuit to ground failure

The control module has detected a short to ground in the electrical circuit that powers the DEF (Diesel Exhaust Fluid) tank heater valve/actuator.

• MAGNUM AFS Connect
• Steiger 580 Quadtrac
• Steiger 535
• 240 Series Axial-Flow Combines
• Farmall 40, 45, and 50 CVT tractors
• Case IH 9900 Sugar Cane Harvesters

1. 1

   Stop the engine and let it cool completely before starting work. Do not start the engine during the diagnostic procedures.

2. 2

   Hook up the Electronic Service Tool (EST) laptop to pull and verify active codes (often accompanied by F-3363-05).

3. 3

   Inspect the wiring plugs at the DEF pump and the solenoid at the back of the motor for a pushed-back pin, which is a highly common cause for this fault. Check for any damaged, loose, or corroded pins, as well as debris or water intrusion.

4. 4

   Trace the wiring harness leading to the DEF tank heater valve/actuator and look for chafing, bare wires, or areas where the harness may be rubbing against the chassis and shorting to ground.

1. 1

   Pull the machine into the shop and ensure the engine is off and cooled down.

   Ensure the engine is off and cooled down.

2. 2

   Locate the DEF tank heater valve (actuator/solenoid) and disconnect its electrical plug.

   Disconnect the electrical plug from the DEF tank heater valve.

3. 3

   Carefully inspect the connector. If you find a pushed-back pin, re-seat the pin properly into the connector housing so it makes full contact.

   Re-seat any pushed-back pins properly into the connector housing.

4. 4

   Use a multimeter to test the harness for a short to ground. If a short is found in the wiring, repair or replace the damaged section of the harness.

   Test the harness for a short to ground and repair or replace if damaged.

5. 5

   If the wiring is intact and the pins are seated correctly, the DEF tank heater valve itself likely has an internal short to ground. Remove the faulty valve and install a replacement.

   Replace the DEF tank heater valve if it has an internal short to ground.

6. 6

   Reconnect all wiring plugs and ensure they are seated correctly.

   Ensure all wiring plugs are seated correctly.

7. 7

   Connect the EST laptop, clear the fault codes, and run a fault verification test.

   Clear the fault codes and run a fault verification test.

8. 8

   Start the tractor and run it until it reaches normal operating temperature to ensure the code does not return and that there are no coolant leaks around the heater valve.

   Run the tractor to normal operating temperature to verify the repair and check for coolant leaks.