Case IH F-729-06 - ECU – Engine Control Unit (ECU): Intake air heater ECU driver has an over-temperature error

The internal driver circuit within the control module that commands the intake air heater relay has overheated. This is typically caused by excessive current draw, such as a short circuit in the wiring, a shorted relay, or an internal failure of the ECU driver itself.

• MAGNUM AFS Connect
• 240 Series Combines (Axial-Flow)
• A8000 Sugar Cane Harvester
• A8800 Sugar Cane Harvester

1. 1

   Check the wiring harness between the Engine ECU and the intake air heater relay for chafed wires, melted insulation, or shorts to ground

2. 2

   Test the intake air heater relay for internal shorts, as a shorted coil will pull excessive amperage

3. 3

   Check the intake air heater element (grid heater) for proper resistance and ensure its main power connections are not shorting against the engine block

4. 4

   Test the ECU driver for internal failure if the wiring, relay, and heater element test within specification

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent accidental shorts during testing.

2. 2

   Inspect and Repair Wiring

   Trace the circuit from the ECU to the intake air heater relay. Repair or replace any damaged sections of the wiring harness.

3. 3

   Replace the Relay

   If the intake air heater relay fails a resistance test or shows signs of internal shorting/melting, replace it.

4. 4

   Replace the Heater Element

   If the intake air heater element is shorted to ground, remove the intake piping, unbolt the heater element from the intake manifold, and install a new unit with fresh gaskets.

5. 5

   Address the ECU

   If the wiring, relay, and heater element are all in good working order but the code persists, the ECU has suffered internal driver damage. The ECU will need to be repaired by a specialized module rebuilder or replaced and reprogrammed by an authorized Case IH dealer.

6. 6

   Clear Codes

   Reconnect the battery, clear the fault codes using a diagnostic tool, and cycle the key to verify the code does not return during the pre-heat cycle.