New Holland ENG 339 – Engine Control Module (ECM): Idle Shutdown Vehicle Accessory Relay Voltage is too low.

The Engine Control Module (ECM) commands the idle shutdown accessory relay ON, but detects that the pulse width modulated (PWM) signal is NOT at system voltage. This typically indicates a short circuit to ground in the relay, the OEM wiring harness, or the connectors.

• T8 Series
• T8.390
• T9 Series
• T9000 Series
• CR Series
• CR9090
• CX Series
• CX8080
• CX8090
• SP Series
• SP410F

1. 1

   Verify ECM Parameters: Ensure the ECM Idle Shutdown feature is correctly configured in the software (parameter set to 'Installed')

2. 2

   Visual Inspection: Locate the idle shutdown relay and inspect the relay, OEM harness, and connectors for physical damage, rubbed wires, or moisture

3. 3

   Grounding Check: Verify the grounding configuration using your specific machine's wiring diagram

4. 4

   Circuit Testing: Use a multimeter to test the relay driver circuit for a short to ground (low voltage) between the ECM and the relay

1. 1

   Power Down

   Turn the keyswitch to the OFF position and disconnect the battery ground to ensure safety.

2. 2

   Clean Connectors

   If moisture or debris is found in the harness connectors during the diagnostic checks, dry and clean the connectors using an approved electronic contact cleaner.

3. 3

   Repair Wiring

   If a short to ground is found in the OEM harness (e.g., a rubbed wire touching the chassis), repair the damaged section of the wire and secure it in a protective loom.

4. 4

   Replace the Relay

   If the wiring harness tests good but the circuit still shorts to ground when commanded on, the internal coil of the idle shutdown relay has likely failed. Replace the relay.

5. 5

   Validate the Repair

   Reconnect the batteries. Perform a key cycle, start the engine, and let it idle for at least 1 minute.

6. 6

   Clear Codes

   The fault code status on your diagnostic tool should change to INACTIVE, and the amber CHECK ENGINE lamp will turn off. Use the "Reset All Faults" command in your electronic service tool to clear the history.