Case IH 3144 – Engine Controller (Engine ECU / EDC): Grid Heater Switch Off Test (Voltage Drop Too Low)

During a self-test of the cold-start emissions system, the Engine Control Module (ECM) switched off the intake grid heater circuit and detected that the voltage drop was lower than the expected threshold. This indicates the grid heater is not drawing the required electrical current, typically caused by an open circuit, a blown high-amperage fuse, a failed grid heater relay, or a burned-out grid heater element.

• Case IH Magnum 235 - 340 (Series 4)
• Case IH Puma Series (e.g., Puma 175, 185, 200)
• Case IH Axial-Flow Combines (e.g., 5130, 6130, 7140)
• Case IH Steiger Series

1. 1

   Verify battery voltage and ensure all battery terminals and chassis grounds are clean and tight.

2. 2

   Check the high-current fuse (often a 300A blade fuse) located in the junction/fuse block that protects the grid heater circuit.

3. 3

   Inspect the heavy-gauge wiring between the battery, the grid heater relay, and the grid heater element on the intake manifold. Look for chafed wires, loose retaining nuts, or heavy corrosion.

4. 4

   Test the grid heater relay. Apply 12V to the control terminals and verify if the relay clicks and provides continuity across the high-current terminals. A relay that clicks but passes no current is faulty.

5. 5

   Disconnect the power cable from the grid heater element and measure the resistance across its terminals with a multimeter. It should have very low resistance (typically under 1 ohm). If it reads as an open circuit (infinite resistance), the element is burned out.

1. 1

   Disconnect Power

   Turn off the machine ignition and disconnect the negative battery cable to prevent accidental shorts, as the grid heater circuit carries very high amperage.

2. 2

   Access the Components

   Locate the grid heater relay and the grid heater element (mounted on the engine air intake manifold).

3. 3

   Replace the Fuse (if applicable)

   If the 300A fuse is blown, unbolt it from the junction block, install a new fuse, and verify there are no shorts to ground in the main power cable before proceeding.

4. 4

   Replace the Relay (if faulty)

   Disconnect the electrical connectors from the grid heater relay. Remove the mounting hardware, detach the relay, and install the new unit. Reconnect the control and power cables securely.

5. 5

   Replace the Grid Heater Element (if faulty)

   Disconnect the heavy-gauge power cable from the grid heater element. Unbolt the grid heater element from the intake manifold. Clean the mating surfaces thoroughly. Install the new grid heater element using a new 0.3mm gasket. Reattach the power cable and torque the retaining nuts to OEM specification.

6. 6

   Reassembly & Clearing Codes

   Reconnect the negative battery cable. Use a diagnostic service tool to clear fault code 3144 from the Engine ECU. Cycle the key and perform a cold start to verify the code does not return.