Case IH 3166 (DTC 64B5) - ECU – Engine Control Unit (Engine ECU): Fuel filter heater actuator is shorted to battery voltage

The Electronic Control Unit (ECU) monitors the fuel filter heater relay (K-024) signal circuit. If the ECU detects a short-to-battery condition on this circuit for a period greater than 200 milliseconds, it logs this fault code.

• MAXXUM T4E
• Magnum 235-340 (Series 4)
• Puma series (165, 180, 195, 210, 225)
• Steiger series
• Farmall models
• Axial-Flow 240 Series
• Axial-Flow 5130

1. 1

   Locate the fuel filter heater relay (K-024), remove it, and inspect the terminals for corrosion, melting, or bridging that could cause a short.

2. 2

   Disconnect the harness at the Engine ECU (A-095) and at the relay. Use a multimeter to check for continuity between the relay signal circuit wire and the battery positive terminal to see if the wiring harness is shorted to power.

3. 3

   Disconnect the wiring at the fuel filter heater actuator (located on the fuel filter housing) and check the heater element for an internal short circuit.

4. 4

   Ensure the charging system/alternator is not overcharging and that no external power supplies have been improperly wired into the engine harness.

1. 1

   Power Down

   Turn off the ignition and disconnect the negative battery cable to prevent electrical damage during testing.

2. 2

   Isolate the Short

   Based on the diagnostic checks, determine if the short is in the relay, the wiring harness, or the heater actuator itself.

3. 3

   Replace the Relay

   If the relay is internally shorted to battery voltage, replace it with a new OEM relay.

4. 4

   Repair the Harness

   If the multimeter test reveals a short in the wiring, trace the harness from the ECU to the fuel filter housing. Look for chafed wire insulation rubbing against the engine block or a positive battery cable. Splice and heat-shrink the damaged wire, or replace the harness section.

5. 5

   Replace the Heater Actuator

   If the short is inside the fuel filter heater element, drain the fuel filter housing, unscrew the faulty heater element/bowl, and install a new heater kit.

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use the in-cab diagnostic display or an electronic service tool to clear the inactive fault codes. Start the engine and verify the code does not return.