New Holland ENG 398 – Engine Control Module (ECM / Engine Controller): Rear Timing current is too low

The electrical current flowing to the rear timing actuator on the fuel injection pump is below the minimum threshold expected by the controller. This typically points to an open circuit, high resistance in the wiring harness, a disconnected plug, or a failed internal coil within the rear timing actuator itself.

• TG215
• TG230
• TG245
• TG255
• TG275
• TG285
• TG305
• T8000 Series Tractors
• Combines
• Forage Harvesters

1. 1

   Inspect the wiring harness and connectors between the Engine ECM and the CAPS pump rear timing actuator for obvious signs of damage, chafing, corrosion, or loose pins.

2. 2

   Disconnect the harness at the CAPS pump and measure the resistance of the rear timing actuator coil. An infinite reading (OL) indicates an open internal coil.

3. 3

   Check for continuity in the wiring harness from the ECM connector to the actuator connector. Also, check for a short to ground or short to voltage in these wires.

4. 4

   Check the transient suppressor and ICV (Injection Control Valve) stator circuit, as a failure in the suppressor can sometimes trigger actuator current codes.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts or ECM damage during the repair.

2. 2

   Access the CAPS Pump

   Locate the CAPS injection pump on the engine and identify the rear timing actuator connection.

3. 3

   Repair/Replace Wiring

   If the diagnostic tests revealed a broken wire or corroded connector, repair the wiring or install a replacement CAPS pump harness kit.

4. 4

   Replace the Actuator / Pump

   If the rear timing actuator coil is internally open, the actuator must be replaced. Note: While some components like the ICV stator/distributor can be replaced individually, severe actuator failures on CAPS pumps often require replacing or rebuilding the entire CAPS injection pump assembly.

5. 5

   Reassembly

   Reconnect all electrical connectors securely.

6. 6

   Clear Codes and Test

   Reconnect the battery, turn the key on, and use a diagnostic tool to clear the ENG 398 fault code. Start the engine and verify that the code does not return and the engine runs smoothly without timing or fueling issues.