Case IH 3167 (DTC 74B5) - ECU – Engine Electronic Control Unit (ECU): Fuel filter heater actuator is shorted to ground

The Electronic Control Unit (ECU) monitors the signal circuit for the fuel filter heater relay (designated as relay K-024). If the ECU detects a short to ground condition in the K-024 signal circuit, it will log this fault.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Puma series
• Magnum MX series (MX210, MX230, MX255, MX285)
• Farmall series (40, 45, 50, 95U, 105U, 115U)

1. 1

   Verify that the tractor's battery power supply has not been connected to an external power supply (like a jump box or external charger). If connected, disconnect and test for normal operation.

2. 2

   Check the machine's charging system for over-voltage or erratic voltage faults.

3. 3

   Inspect the wiring harness between the ECU (A-095) and the K-024 relay for visible chafing, melting, or pinching that could cause a short to the chassis ground.

4. 4

   Rule out a faulty Central Control Unit (CCU) or Universal Control Module (UCM).

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Locate the Relay

   Access the main cab relay/fuse panel and locate relay K-024 (Fuel heater relay).

3. 3

   Test the Relay

   Remove the K-024 relay and test the coil resistance. If the coil is burnt out or internally shorted to ground, replace the relay.

4. 4

   Test the Circuit

   With the relay removed, use a multimeter to check the continuity of the signal circuit wire running from the relay block to the ECU (A-095). If there is continuity to ground, trace the harness and repair the shorted wire.

5. 5

   Test the Actuator/Heater

   Inspect the fuel filter heater actuator element on the fuel filter housing. Unplug the heater and check for an internal short to ground. If the heater element is shorted, replace the fuel filter heater assembly.

6. 6

   Reassemble and Clear

   Reinstall the relay and connections, reconnect the battery, turn the key on, and clear the fault codes. Run the engine to verify the code does not return.