Case IH F-1485-13 - ECU – Engine Control Unit (ECU): ECU after run power interruption

When the ignition key is turned off, the Engine ECU does not shut down immediately. It enters an after-run phase where it requires continuous, unswitched battery power for 60 to 90 seconds to save operating data, park electronic actuators, and run the DEF/AdBlue system purge cycle. If the unswitched power supply to the ECU is cut off before this process finishes, the ECU logs this fault code upon the next startup.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240
• Steiger
• Optum
• Puma series
• N Series Loaders
• compact track loaders

1. 1

   Operator Interview: Verify if the operator is turning off the master battery disconnect switch immediately after turning off the ignition key.

2. 2

   Battery & Ground Connections: Inspect the battery terminals, chassis grounds, and the specific ground strap for the Engine ECU. Loose or corroded connections can cause a voltage drop during the after-run phase.

3. 3

   Relay Testing: Locate the ECU Main Power Relay. Check for internal resistance, sticking contacts, or a weak coil that might cause it to drop out prematurely.

4. 4

   Harness Inspection: Check the unswitched power wiring harness between the battery, the main relay, and the ECU for chafing, loose pins, or corrosion.

1. 1

   Correct Shutdown Procedure

   If the issue is operator-induced, instruct the operator to wait at least 2 minutes after turning off the ignition key before turning off the master battery disconnect switch. This allows the DEF purge and ECU after-run to complete.

2. 2

   Clean Power Supply

   Disconnect the batteries and thoroughly clean all battery posts, terminals, and the ECU ground connections on the engine block/chassis.

3. 3

   Replace the ECU Main Relay

   If the operator is shutting down the machine correctly but the code persists, swap the relay with a known good relay of the same type from the fuse panel (e.g., a lighting relay). If the fault does not return, replace the relay permanently.

4. 4

   Harness Repair

   If the relay is good, use a multimeter to perform a voltage drop test on the unswitched power wire leading to the ECU while the key is off. Repair any damaged wiring or replace the harness if internal breaks are found.

5. 5

   Clear and Verify

   Clear the fault code using the diagnostic tool. Start the engine, let it idle, and perform a normal key-off shutdown. Wait 2 full minutes, then turn the key back on to verify the code does not return.