Case IH 3059 – Engine Control Module (ECM / ECU): ECU Afterrun was Interrupted / ISM-IDI ECU Main Power Relay Failed Closed / F5C Engine Controller Main Relay Circuit (Terminal 30) - Stuck Main Relay Error

When the machine is turned off, the Engine Control Module (ECM) requires a brief "after-run" period where it remains powered to save operating data and park actuators. This code triggers when the main power relay (Terminal 30 circuit) fails to open (gets stuck closed) or if the after-run sequence is interrupted by a wiring fault or premature power loss.

• Farmall
• skid steer
• SR160
• SR250
• SV340
• TR270
• Magnum Series (235-340 Series 4)
• 1650M
• 2050M
• 575N
• 580N

1. 1

   Test the ECU Main Power Relay for a mechanically stuck closed condition by checking for continuity between Terminal 30 and Terminal 87 while the machine is completely off.

2. 2

   Inspect the F5C engine controller main relay circuit (Terminal 30) for wiring damage, corrosion, or a short to battery voltage that might be bypassing the relay.

3. 3

   Verify if the battery disconnect switch was turned off too quickly after key-off, which manually cuts power before the ECM finishes its after-run sequence.

1. 1

   Power Down

   Turn the ignition key to the OFF position and wait at least 60 seconds to see if the ECM powers down.

2. 2

   Locate the Relay

   Access the main electrical distribution box / fuse panel and locate the ECU Main Power Relay (refer to the specific machine's fuse diagram, often labeled "ECU Main" or "Main Power Relay").

3. 3

   Replace the Relay

   If the relay tested as stuck closed (failed closed), pull the faulty relay and replace it with a new OEM 5-pin relay.

4. 4

   Repair Wiring (If Applicable)

   If the relay is functioning normally but the code persists, trace the Terminal 30 wire from the relay block to the ECM. Repair any frayed wires or short circuits.

5. 5

   Clear and Reset

   Reconnect power, turn the key to the ON position, and use a diagnostic tool (like the CNH EST) to clear the inactive 3059 fault code. Cycle the key off and wait to ensure the ECM after-run completes without interruption.