Case IH 1080.04 - ACML – ACML: Sensor Supply 2 Circuit Low Voltage or Shorted to Ground

The system's ECU detects that the voltage is below specification (typically dropping below 4.5V) on the 5-volt sensor supply circuit. This condition is generally caused by insufficient power supply, faulty/shorted wiring, a malfunctioning sensor pulling the reference voltage down, or a bad internal voltage regulator within the control unit.

• VESTRUM CVX
• Puma 175 CVX
• Magnum 260
• Magnum 290
• Steiger 500
• Maxxum 135 Multicontroller

1. 1

   Disconnect the sensors operating on the Sensor Supply 2 circuit one at a time to see if the 5V reference returns to normal, indicating a malfunctioning sensor

2. 2

   Inspect the wiring harness connected to the Armrest Control Module for chafing, pinched wires, or exposed copper that could cause a short to ground

3. 3

   Check the main power supply and fuses feeding the Armrest Control Unit to ensure it is receiving sufficient voltage

4. 4

   Test the voltage directly at the ACML output pins to verify if the internal voltage regulator is functioning

1. 1

   Turn off the machine and disconnect battery power before servicing the electrical system.

2. 2

   Access the Armrest Control Module (ACML) located inside the cab's armrest console.

3. 3

   Using a multimeter, test the Sensor Supply 2 circuit pins for continuity to ground to confirm if a short exists in the harness.

4. 4

   If a short to ground is found in the wiring, repair or replace the affected section of the wiring harness.

5. 5

   If the wiring is intact, reconnect battery power and test the 5V reference circuit while unplugging sensors on that circuit one by one.

   Replace any sensor that restores the 5V reference when disconnected.

6. 6

   If no sensors or wiring faults are found and the ACML is still outputting low voltage (below 4.5V), remove the mounting screws and harness connectors to extract the ACML.

   This indicates the ACML has suffered an internal failure (bad voltage regulator).

7. 7

   Install the replacement Armrest Control Module, reconnect the harnesses, and perform any necessary factory calibrations for the armrest controls.

8. 8

   Clear the fault codes and verify that 1080.04 does not return.