Case IH 46.00 - ACML – ACML: Internal CPU/ADC reference voltage (5000mV) does not match.

The internal 5-volt (5000mV) reference voltage generated by the CPU's Analog-to-Digital Converter (ADC) inside the control module is out of specification, mismatched, or failing. This typically points to a hardware failure within the module itself, though an external short on a 5V sensor circuit can sometimes pull this voltage down.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Maxxum Series
• Case IH Puma Series
• Case IH Vestrum CVXDrive
• Case IH Optum Series

1. 1

   Cycle Power & Clear Codes: Restart the tractor to see if the code is an active hard fault or a stored intermittent error. Attempt to clear the code using the tractor's diagnostic menu, but note that clearing it without fixing the root cause will result in the code returning.

2. 2

   Inspect Armrest Controls: Check the EHR control unit and armrest dispenser controls for physical damage, sticking levers, or liquid spills that may have shorted the internal circuitry.

3. 3

   Check 5V Sensor Circuits: Before condemning the ACML, inspect the wiring harness connecting to the armrest. A dead short in an external sensor or wiring harness that relies on the ACML's 5V reference can pull the internal ADC voltage down, triggering the 46.00 code.

4. 4

   EST Diagnostics: Connect the CNH Electronic Service Tool (EST) to verify if the ACML is communicating properly on the CAN bus and to monitor the live 5V reference data.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Module

   Disassemble the Multicontroller armrest console to access the ACML ECU.

3. 3

   Remove the Faulty Module

   Carefully unplug the multi-pin harness connectors from the ACML. Remove the mounting screws (typically M3 x 0.5 x 14.4mm screws) securing the module.

4. 4

   Install the New Module

   Mount the replacement ACML and securely reconnect the wiring harnesses.

5. 5

   Reassemble and Power Up

   Reassemble the armrest console and reconnect the battery.

6. 6

   Programming/Calibration

   A new ACML module will require software configuration and calibration using the CNH EST (Electronic Service Tool) to sync with the tractor's specific transmission and hydraulic options.