Case IH 519048-03 - BCM – BCM: ATC inlet air temperature sensor out of range - high

The ATC (Automatic Temperature Control) inlet air temperature sensor (cab return air sensor) is reading 'out of range - high'. This means the voltage signal sensed by the controller is higher than the component's normal operating limit, typically caused by an open input wire, an open ground wire, or an input wire shorted to a high voltage source.

• MAGNUM AFS Connect
• Magnum 200
• Magnum 215
• Magnum 220
• Magnum 225
• Magnum 235
• Magnum 240
• Magnum 245
• Magnum 250
• Magnum 255
• Magnum 275
• Magnum 280
• Magnum 290
• Magnum 305
• Magnum 310
• Magnum 335
• Magnum 340
• Magnum 380
• MX100C
• MX180
• MX200
• MX215
• MX285
• Steiger / STX 4WD Series 280 through 535
• Steiger / STX 4WD Series 485
• Puma Series 115 through 225
• Maxxum Series 100 through 140
• CX50
• CX60
• CX70
• CX80
• CX90
• CX100
• Patriot 4440

1. 1

   Check Cab Grounds: Ensure all cab grounds are clean and secure. The HVAC system grounds are typically located at the back of the cab on the left side (relative to a forward-facing seated position). With no current flowing, resistance should be less than 1 ohm from the battery post to the frame.

2. 2

   Locate the Sensor: Raise the seat for the best access. The return air sensor is located on the divider between the HVAC plenum and the electrical distribution area, specifically on the right side.

3. 3

   Compare Resistance Values: For the ATC system to function properly, the return air sensor and the evaporator temperature sensor must have identical resistance-to-temperature values. Test the resistance of both sensors to see if the inlet/return sensor has failed open.

4. 4

   Inspect Wiring: Check the sensor's wiring harness for an open circuit, a broken ground wire, or a short to a 12V power source.

1. 1

   Turn off the machine and disconnect the battery

   Turn off the machine and disconnect the battery to prevent electrical shorts.

2. 2

   Raise or remove the operator seat

   Raise or remove the operator seat to access the HVAC plenum and electrical distribution area.

3. 3

   Locate the inlet/return air temperature sensor

   Locate the inlet/return air temperature sensor on the right side of the HVAC divider.

4. 4

   Disconnect the sensor's electrical connector and inspect

   Disconnect the sensor's electrical connector and inspect the pins for corrosion, pushed-out terminals, or moisture.

5. 5

   Verify continuity on the ground circuit and check the signal wire

   Using a multimeter, verify continuity on the ground circuit and check the signal wire back to the ATC controller for opens or shorts.

6. 6

   Remove the faulty sensor

   If the wiring is intact but the sensor fails the resistance test (showing an open internal circuit), remove the faulty sensor.

7. 7

   Install the new temperature sensor

   Install the new temperature sensor and reconnect the wiring harness.

8. 8

   Reconnect the battery, power on the machine, and clear the fault codes

   Reconnect the battery, power on the machine, and clear the fault codes. Verify that the ATC system now regulates the cab temperature correctly.