Case IH 3156 – Engine Control Module (ECM) / Electronic Diesel Control (EDC): Grid Heater Relay - No Load

The engine's control module is commanding the intake grid heater relay to activate, but it is not detecting any electrical load (current draw) on the circuit. This condition typically indicates an open circuit, such as broken wiring, a disconnected harness, or a completely failed relay.

• Case IH Magnum 235 - 340 (Series 4)
• Case IH Puma 165, 180, 195, 210, 225 CVX
• Case 580 Super N

1. 1

   Inspect the wiring harness connecting the ECM to the grid heater relay for any broken wires, chafing, or disconnected plugs.

2. 2

   Check the heavy-gauge power supply cables running from the battery to the relay, and from the relay to the intake grid heater, ensuring the connections are tight and free of corrosion.

3. 3

   Test the grid heater relay itself to see if the internal coil has failed (open circuit).

1. 1

   Disconnect battery

   Disconnect the machine's battery to prevent accidental shorts when working with the high-amperage grid heater circuit.

2. 2

   Locate relay

   Locate the grid heater relay (location varies by model, but it is typically mounted near the engine frame bracket or intake manifold).

3. 3

   Disconnect connector

   Disconnect the electrical connector from the relay.

4. 4

   Inspect and repair wiring

   Inspect the wiring. If broken or disconnected wiring is found, repair the harness.

5. 5

   Remove defective relay

   If the wiring is intact, detach the mounting hardware and remove the defective grid heater relay.

6. 6

   Install new relay

   Install the new relay and reconnect the electrical harness and high-amperage cables.

7. 7

   Verify repair

   Reconnect the battery, turn the key to the ON position to allow the ECM to cycle the grid heater, and verify that the fault code is cleared.