New Holland ENG 3270 – Engine Control Module (ECM) / EDC: Grid Heater Switch On Test - Voltage Drop Too Low

When the engine is started in cold conditions, the ECM commands the intake air grid heater to turn on to warm the incoming air. A voltage drop that is 'Too Low' means the grid heater circuit is not drawing the expected amperage. This indicates an open circuit somewhere in the system—most commonly a blown high-amp fuse, a failed grid heater power relay, a broken/disconnected heavy-gauge wire, or a burned-out grid heater element.

• T6 Series
• T7 Series
• T8 Series
• T6.175
• T7.175
• T7.210
• T8.380
• CR9090
• CX8080
• CX8090
• B110
• FB100

1. 1

   Fuse Inspection: Locate the main high-amperage fuse block and check the grid heater fuse (typically a 200A Mega fuse) for an open/blown condition.

2. 2

   Relay Testing: Locate the grid heater power relay. Verify that the ECM is sending the low-amp trigger voltage to the relay coil during a cold start sequence. If the trigger signal is present but the relay does not click or bridge power to the heavy-gauge output cable, the relay is faulty.

3. 3

   Wiring & Connection Check: Visually inspect the heavy-gauge cables running from the battery to the relay, and from the relay to the grid heater element. Look for loose terminal nuts, severe corrosion, or broken wires.

4. 4

   Element Continuity: Disconnect the power cable at the intake grid heater and use a multimeter to measure the resistance of the heater element to ground. If it reads as an open circuit (infinite resistance), the heater element is burned out.

1. 1

   Disconnect Power

   Disconnect the negative battery cable. Warning: The grid heater circuit carries extremely high amperage (up to 200 amps) and can cause severe burns, sparks, or electrical fires if accidentally shorted to ground during repair.

2. 2

   Access the Components

   Locate the faulty component identified during your diagnostic checks (fuse block, relay on the firewall/bracket, or the heater element on the intake manifold).

3. 3

   Replace the Faulty Component

   If the fuse is blown: Unbolt the old fuse and install a new 200A mega fuse. (Note: Always check the heavy-gauge wiring for a short-to-ground that may have caused the fuse to blow before restoring power). If the relay failed: Remove the retaining nuts holding the heavy-gauge cables to the relay studs. Unplug the trigger wire harness. Unbolt the relay from its mounting bracket, install the new relay, and torque the electrical connections securely. If the wiring harness is damaged: Remove the old harness and route the replacement harness, ensuring it is secured away from high-heat exhaust components and moving parts. If the grid heater element failed: Remove the intake air piping connected to the manifold. Unbolt the grid heater block. Clean the mating surfaces, install the new grid heater block with new gaskets, and torque the bolts to OEM specifications.

4. 4

   Reassembly

   Reconnect the heavy-gauge wiring and ensure all terminal nuts are tight. Reconnect the negative battery cable.

5. 5

   Verification

   Clear the fault codes using a diagnostic scan tool. Turn the key to the ON position in cold conditions to verify the grid heater engages (the dash light should illuminate, and a voltage drop should be noticeable on the battery gauge). Ensure code ENG 3270 does not return.