Case IH 45.00 - ACML – ACML: Error on voltage 12VRef supply detected, supply will be switched OFF and all connected devices will go to 'error state'.

The controller's processor monitors the 12-volt reference (12VRef) circuit, which supplies regulated power to various switches, sensors, and joysticks. When the system detects that the 12VRef signal has failed a limits test (typically due to a short circuit, overload, or out-of-range voltage), the controller automatically shuts off this supply to protect the circuit board from hardware damage. Because the supply is cut, all devices relying on that 12V reference lose power and subsequently report an 'error state'.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Maxxum Series
• Maxxum 135 Multicontroller Activedrive 8
• Case IH Puma Series
• Case IH Magnum and STX Steiger Series

1. 1

   Use the AFS Pro display (or Pro 1200 monitor) to verify if the fault is currently Active or Inactive. If inactive, attempt to clear the code to see if it returns.

2. 2

   Isolate connected devices (such as autoguidance switches, creeper switches, and armrest joysticks) to check if a short in a single connected device is pulling down the entire 12VRef circuit.

3. 3

   Inspect the wiring harness connecting the ACML to the armrest controls. Look for chafed wires causing a short to ground (ACML GND to CAB GND).

4. 4

   If all external sensors, switches, and wiring harnesses test good and have no shorts, perform a module limits test to verify the ACML's internal power supply generation.

1. 1

   Disconnect devices

   Disconnect the devices powered by the ACML's 12V reference one by one.

2. 2

   Cycle power

   Cycle the key/power after each disconnection to see if the 45.00 fault code clears and the 12VRef supply is restored.

3. 3

   Replace faulty component

   If disconnecting a specific switch or joystick clears the code, replace that faulty component.

4. 4

   Replace ACML controller

   If the code persists with all external devices disconnected, the internal 12V reference generator on the ACML circuit board has failed. You must replace the ACML controller PCB.

5. 5

   Calibrate new module

   After replacing the ACML, the new module may require calibration or software flashing via the CNH Electronic Service Tool (EST) to sync with the tractor's CAN network.