Case IH 16118 – ATC (Automatic Temperature Control): Outside air sensor shorted to ground

The control module is receiving a voltage signal from the outside air temperature sensor that is near zero volts, interpreted as a direct short to ground. This can be caused by an internally shorted sensor, a pinched/chafed wire touching the machine's chassis, or severe moisture intrusion in the connector.

• Puma/Mid Range Magnum
• Maxxum
• Case IH Magnum Series
• Case IH Puma Series
• Case IH Steiger Series
• Case IH Farmall Series

1. 1

   Visually inspect the outside air temperature sensor and wiring harness for visible chafing, pinched wires, or melted insulation.

2. 2

   Perform a disconnect test: Unplug the sensor's electrical connector, turn the key ON, and check active fault codes. If the code changes to 16117, the sensor is internally shorted. If it remains 16118, the short is in the wiring harness.

3. 3

   Using a multimeter, test the signal wire from the sensor connector back to the ATC module for continuity to ground to locate harness shorts.

4. 4

   Inspect the pins inside the sensor connector for green corrosion or water intrusion that could bridge the pins and cause a short to ground.

1. 1

   Power Down

   Turn off the tractor, remove the key, and turn off the battery disconnect switch to prevent electrical spikes.

2. 2

   Locate the Sensor

   Access the outside air temperature sensor based on your specific model's cab layout.

3. 3

   Disconnect

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

4. 4

   Remove the Sensor

   Unclip or unthread the faulty sensor from its mounting bracket.

5. 5

   Install the New Part

   Snap or thread the new outside air temperature sensor into the factory mounting location.

6. 6

   Reconnect

   Plug the electrical harness back into the sensor. Ensure the weather-pack seal clicks into place to prevent future moisture intrusion.

7. 7

   Clear Codes

   Turn the battery disconnect back on, turn the ignition key to the ON position, and use the tractor's A-post display or Pro 700/1200 monitor to navigate to the ATC diagnostic menu and clear the inactive fault codes.

8. 8

   Verify Operation

   Run the tractor and verify that the climate control system is reading an accurate outside ambient temperature and that the A/C compressor cycles properly.