Case IH 3764 (DTC F561) - ECU – Engine ECU: ECU after run power interruption

The unswitched battery power supply to the ECU was cut off before the module could complete its programmed 'after-run' shutdown sequence, which is required to save operating parameters and run the DEF purge cycle.

• MAXXUM T4E
• 230 Series Combines (7230, 8230, 9230)
• 240 Series Combines (7240, 8240, 9240)
• Magnum/Steiger series
• STM N Series Loaders

1. 1

   Verify operator shutdown procedure (most common cause) to ensure the master battery disconnect switch is not turned off immediately after the ignition key.

2. 2

   Inspect the ECU power relay (often K-14) to see if it is dropping out prematurely or sticking.

3. 3

   Check ECU unswitched power fuses (often F-01) for partial blows or loose seating.

4. 4

   Inspect battery terminals, master disconnect switch terminals, and ECU ground straps for corrosion or loose connections that could cause a momentary voltage drop.

1. 1

   Operator Education

   If the diagnostic checks reveal the operator is cutting the master power too early, educate them to wait until the DEF purge cycle is completely finished (listen for the DEF pump to stop running) before turning off the battery disconnect switch. Clear the code and test.

2. 2

   Relay Replacement

   If the operator procedure is correct, swap the ECU Power Relay (K-14) with a known good relay of the same type. If the code does not return, replace the relay permanently.

3. 3

   Wiring Repair

   Test the voltage at the ECU's unswitched power pins while the key is off. If the voltage drops unexpectedly, trace the wiring harness back to the battery. Repair any chafed wires, clean corroded grounds, and tighten all terminal connections.

4. 4

   Disconnect Switch Replacement

   If the master battery disconnect switch is found to be internally loose or failing (causing intermittent power loss even when left in the 'ON' position), remove the battery cables, unbolt the faulty switch, and install a new OEM disconnect switch.