Case IH 16131 – ATC (Automatic Temperature Control) module or Armrest/Cab Controller: Low pressure switch (+) input shorted to ground

This code indicates an electrical fault in the machine's HVAC (Air Conditioning) system. The code specifically flags that the positive (+) input wire for the A/C low-pressure switch has a short circuit to ground, meaning the voltage is being incorrectly routed to the chassis/earth before returning to the controller.

• Puma/Mid Range Magnum
• Maxxum
• Puma series (140, 165, 180, 195, 210, 225 CVX)
• Magnum series
• Steiger series
• T6000 series
• T7 series
• T8 series

1. 1

   Locate the A/C low-pressure switch, which is threaded into the A/C suction line.

2. 2

   Disconnect the switch and visually inspect the wiring harness leading back to the cab/ATC module for chafed insulation, pinched wires, or melted loom.

3. 3

   With the switch disconnected and the machine powered on, use a multimeter to check for continuity to ground on the positive pin of the harness connector to identify a harness short.

4. 4

   Check the switch pins with a multimeter for an internal short to the switch housing or body.

5. 5

   Check for related HVAC codes (e.g., 16132, 16133, 16134) which also point to low-pressure switch circuit failures.

1. 1

   Repair Wiring

   If the diagnostic tests reveal a short in the harness, splice and repair the damaged section of the wire, then wrap it in protective loom.

2. 2

   Replace the Switch

   If internally shorted, disconnect the electrical connector from the low-pressure switch. Unscrew the switch from the A/C line (Note: On most modern Case IH systems, the switch is mounted on a Schrader valve, meaning it can be unscrewed and replaced without discharging or recovering the A/C refrigerant. Verify this on your specific model before removing). Thread the new switch onto the fitting and tighten to OEM specifications. Reconnect the electrical harness.

3. 3

   Clear Codes

   Cycle the key and use the Armrest display or a diagnostic tool to clear the ATC fault codes.

4. 4

   Test Operation

   Turn on the A/C system and verify that the compressor clutch engages and the code does not return.