Case IH 3342 – Engine Control Module (ECM / ENG): Power Stage Air Heater 2 Actuator - No Signal

The engine's electronic control system has detected an open circuit or a complete loss of electrical feedback from the secondary grid heater relay (the actuator responsible for warming intake air during cold starts). The "No Signal" condition means the controller is commanding the heater to turn on, but is not detecting the expected voltage or continuity on the control circuit.

• Magnum 235-340 (Series 4)
• Steiger series
• Puma series
• Puma 185 CVT
• T8.xxx Series
• 580M Series 2 Loader Backhoes
• W170B wheel loaders
• W190B wheel loaders

1. 1

   Check the Fuses: Inspect the main high-amp fuses or fusible links that supply battery power to the grid heater relay. A blown fuse will cause a loss of signal.

2. 2

   Inspect the Wiring Harness: Trace the wiring from the Engine Control Module (ECM) to the grid heater relay. Look for disconnected plugs, corroded pins, or broken wires (open load).

3. 3

   Test the Relay Coil: Use a multimeter to test the control terminals on the grid heater relay for continuity. An open internal coil will trigger the 3342 code.

4. 4

   Check the Heater Element: Verify that the intake grid heater element itself is not burnt out or shorted, which can sometimes damage the relay.

1. 1

   Disconnect Power

   Disconnect the negative battery cable. The grid heater circuit carries extremely high amperage, and working on it while live poses a severe short-circuit and fire hazard.

2. 2

   Locate the Actuator

   Locate the grid heater relay (Power Stage Air Heater Actuator). It is typically mounted on a bracket near the engine intake manifold or adjacent to the ECM.

3. 3

   Remove Connections

   Disconnect the low-voltage control harness connector from the relay. Then, unbolt the heavy-gauge battery and heater cables from the high-current terminals.

4. 4

   Remove the Relay

   Unbolt the relay mounting hardware and remove the faulty unit.

5. 5

   Install the New Part

   Mount the replacement relay. Reattach the heavy-gauge cables, ensuring the nuts are torqued to OEM specifications to prevent high-resistance arcing. Plug in the low-voltage control connector.

6. 6

   Reassemble and Test

   Reconnect the negative battery cable. Turn the ignition key to the ON position to trigger the cold-start sequence.

7. 7

   Clear Codes

   Use the CNH EASy diagnostic tool (or an equivalent heavy-duty scanner) to clear the inactive 3342 fault code from the Engine ECM.