Case IH 519047-04 - BCM – BCM: ATC (Automatic Temperature Control) outlet air temperature sensor is out of range - low

The control module is receiving a voltage signal from the sensor that is below the minimum acceptable threshold (typically less than 0.1 VDC). This condition usually points to a short to ground in the sensor's wiring circuit or an internally shorted sensor where the resistance has dropped below specification (e.g., less than 50 Ohms, which the system falsely interprets as an extreme high temperature like 293°F/145°C).

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series
• Magnum 400 AFS Connect
• Case IH Steiger AFS Connect series

1. 1

   Visual Inspection: Access the ATC outlet air temperature sensor (typically located in the HVAC ducting or under the operator's seat depending on the cab configuration). Inspect the sensor's electrical connector and wiring harness for chafing, corrosion, or loose pins.

2. 2

   Resistance Test: Disconnect the sensor and measure its internal resistance with a multimeter. If the resistance is extremely low (e.g., under 50 Ohms), the sensor has failed internally and must be replaced.

3. 3

   Wiring Circuit Check: With the sensor disconnected, check the signal wire leading back to the BCM for a short to ground.

4. 4

   Reference Voltage Check: Turn the key ON and verify that the BCM is supplying the correct reference voltage (usually 5V) to the sensor connector.

1. 1

   Turn off the tractor, remove the key, and turn off the master battery disconnect switch.

2. 2

   Locate the ATC outlet air temperature sensor.

   You may need to remove the cab interior trim panels or access the HVAC blower/evaporator housing (often located under the seat) to reach the duct where the sensor is mounted.

3. 3

   Depress the locking tab and disconnect the electrical harness from the sensor.

4. 4

   Twist or unclip the faulty temperature sensor and pull it out of the HVAC housing.

5. 5

   Insert the new OEM temperature sensor into the duct and ensure it is seated securely.

6. 6

   Reconnect the electrical harness, ensuring it clicks into place.

7. 7

   Reassemble any cab trim panels or seat components that were removed.

8. 8

   Turn on the battery disconnect and power up the tractor.

9. 9

   Clear the inactive fault codes using the tractor's display monitor or the Electronic Service Tool (EST).

10. 10

    Run the HVAC system in "Auto" mode to verify that the outlet air temperature regulates correctly and the fault code does not return.