New Holland NH 3117 – Engine Control Unit (ECU): ECU: Self Test Shutoff Paths ( Start Up ) - NOT PLAUSIBLE

The engine will derate to 1800 rpm. This code indicates that the Engine Control Unit (ECU) detected an improper shutdown during its startup self-test. The most common cause is that the ECU power failed while the engine was running, or the engine shutdown process was incorrect (e.g., power was cut via a battery disconnect switch before the ECU could properly power down and save its data).

• T6 series
• T6010
• T6020
• T6030
• T6.140
• T6.180
• T7 series
• T8 series
• T8.350
• T8.380
• TM series
• CR series
• CR960
• CR970
• CR980
• CR6.80
• CR9.90
• CR9080
• CR9090
• CX series
• CX8070
• CX8080
• CX8090

1. 1

   Verify Operator Habits: Confirm if the operator recently used the battery disconnect switch immediately after turning off the key. The ECU requires a brief period to complete its shutdown sequence after the ignition is turned off.

2. 2

   Check Battery Connections: Inspect the battery terminals and cables for loose connections or corrosion that could cause a sudden loss of power while the engine is running.

3. 3

   Test the Battery Disconnect Switch: Check the main battery disconnect switch for internal faults, loose studs, or intermittent contact.

4. 4

   Inspect the Main Relay: Test the main power relay (often located in the relay panel) to ensure it is not dropping out prematurely or failing to supply consistent voltage to the ECU.

5. 5

   Wiring Harness Inspection: Check the ECU power supply wiring for chafing, shorts, or open circuits.

1. 1

   Clear the Code

   If the code was caused by an operator error (cutting the battery switch too early), simply clear the fault code using a diagnostic scan tool.

2. 2

   Educate the Operator

   Ensure the proper shutdown procedure is followed moving forward. The ignition key must be turned off, and the operator must wait for the ECU to completely power down before turning off the master battery disconnect switch.

3. 3

   Replace Faulty Relays

   If the code persists and the main relay is found to be defective or dropping voltage, remove the original relay from the relay panel and install a new OEM main relay.

4. 4

   Replace the Battery Disconnect Switch

   If the master disconnect switch is faulty or has loose internal contacts causing intermittent power loss, disconnect the battery cables, unbolt the old switch, and install a new replacement switch.

5. 5

   Repair Wiring

   If any damaged wiring is found in the ECU power supply circuit, repair or replace the affected harness section.

6. 6

   Final Test

   Start the engine, allow it to run, and perform a proper shutdown. Restart the machine to verify that the NH 3117 code does not return and the engine no longer derates to 1800 rpm.