Massey Ferguson 4376.04 – Engine ECU (EEM4): The DEF Reverse Flow Solenoid Valve Low Voltage

The AGCO SISU POWER EEM4 monitoring system has detected a short circuit to ground on the low side of the DEF pump direction valve (also referred to as the reverse flow solenoid valve).

• 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

1. 1

   Inspect the wiring harness connecting the Engine ECU to the DEF Supply Module for chafed, pinched, or melted wires that could be shorting the low-side control circuit to the chassis ground.

2. 2

   Test the DEF Supply Module operation by temporarily plugging in a known-good module to see if the fault clears.

3. 3

   Verify the Engine ECU internal driver by checking if the fault remains active with a replacement ECU (if wiring is intact and a replacement DEF module does not clear the fault).

1. 1

   Disconnect power

   Turn off the ignition and disconnect the battery to prevent further electrical damage during testing.

2. 2

   Isolate the short

   Disconnect the harness at the DEF Supply Module and at the Engine ECU. Use a multimeter to check for continuity between the DEF pump direction valve low-side pin and the chassis ground.

3. 3

   Repair wiring

   If continuity to ground is found in the harness, locate the chafe or short and repair the wiring.

4. 4

   Replace the DEF module

   If the harness tests perfectly fine, the short is internal to the DEF Supply Module (the direction valve is integrated into this unit). Remove the DEF lines and electrical connectors, unbolt the module, and install the replacement unit.

5. 5

   System reset

   Reconnect the battery. Turn the ignition off for a minimum of 60 seconds, then turn it back on to perform a System Reset. Clear the inactive fault codes using a service tool.