Case IH F-729-04 - ECU – Engine Control Unit (ECU A-095): Intake air heater actuator is shorted to ground

The system has detected a Voltage Below Normal or Shorted to Low Source condition on the intake air heater #1 circuit. The control module monitors the intake air heater relay control circuit, and if a short to ground condition is detected in this circuit, the fault is triggered.

• MAGNUM AFS Connect
• Magnum Tractors (MX210, MX230, MX255, MX285, 275)
• 240 Series Combines
• Farmall series tractors
• Puma series tractors

1. 1

   Verify that the tractor battery power supply has not been connected to an external power supply (like a jump starter). If an external power supply is connected, disconnect it and test the system for normal operation.

2. 2

   Visually inspect the relevant wiring harnesses and connectors for damage, bent or dislocated pins, corroded terminals, or broken wires. Flex the harnesses involved to reveal any intermittent breaks or shorts in the wiring.

3. 3

   Locate the intake air heater relay (designated as K-023). Measure the resistance between K-023 pin 1 and pin 2. The resistance should be between 70 - 130 Ω.

4. 4

   Disconnect the relevant harness connector (e.g., X-911) and check the K-023 control circuit for continuity to ground to confirm the short.

1. 1

   Address Relay Failures

   If the resistance value of the intake air heater relay (K-023) is not within the specified 70 - 130 Ω range, the relay has failed internally. Replace the K-023 relay.

2. 2

   Repair Wiring Harness

   If the relay tests good but a short to ground is found in the control circuit between ECU A-095 and relay K-023, trace the harness to locate the damaged conductor. Repair or replace the shorted section of the wiring harness.

3. 3

   ECU Software Check

   If there is no continuity to ground (no short found) and the relay is functioning properly, check the Engine Control Unit (ECU A-095) for the appropriate software version. Re-flash the ECU if necessary, as directed by OEM service guidelines.