New Holland ENG 3344 – Engine ECU: Power Stage Air Heater 2 Actuator - Signal Low

Electrical fault in the control circuit for the second intake air heater (grid heater) relay. The engine controller is detecting a voltage that is lower than expected on the relay's control line, which typically points to a short-circuit to ground, an open circuit in the wiring harness, or a failed relay coil.

• T8 Series (e.g., T8.350)
• T9 Series (e.g., T9.600, T9.615)
• CR9090
• CX8080 Elevation
• CX8090 Elevation
• Magnum 235-340 (Series 4)

1. 1

   Visually inspect the wiring harness running from the Engine ECU to the Grid Heater Relay for chafed wires shorting against the engine block or frame.

2. 2

   Turn the key switch to the ON position, disconnect the grid heater relay connector, and measure the voltage between terminal 1 of the connector and a known good ground.

3. 3

   If approximately 12V is not indicated during the voltage test, inspect the wiring harness for an open circuit or short to ground.

4. 4

   If 12V is present during the voltage test, remove the grid heater relay and perform a bench test by applying standard control voltage to the coil pins to see if it clicks and the high-current contacts close.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable. The grid heater circuit carries very high amperage, making this a critical safety step.

2. 2

   Locate the Relay

   Locate the Grid Heater Relay. On many New Holland tractors (like the T8/T9), it is mounted on a front frame bracket or near the engine intake manifold.

3. 3

   Inspect the Connector

   Unplug the electrical connector (typically a 2-way Superseal 1.5 plug). Check for pushed-out pins, corrosion, or melted plastic.

4. 4

   Replace the Component

   If the relay failed the diagnostic bench test, unbolt the high-current cables from the relay posts, unbolt the relay from its mounting bracket, and install the new OEM relay. If the connector is damaged, splice in a new pigtail connector.

5. 5

   Reassemble and Clear Codes

   Reconnect the high-current cables, plug in the control connector, and reconnect the battery. Use the CNH Electronic Service Tool (EST) or the machine's onboard diagnostic display to clear the inactive ENG 3344 code. Cycle the key to verify the code does not return during the cold-start grid heater self-test.