Case IH 168-00 - ACM – ACM: System Voltage High

The module is detecting an out-of-range voltage condition (typically an over-voltage spike or an internal hardware failure on the 12V power supply circuit within the module itself).

• MAGNUM AFS Connect
• Case IH Steiger Series
• Case IH Magnum Series
• Case IH Puma and CVX Series

1. 1

   Measure the unswitched and switched battery voltage supplied to the ACM at the harness connector (should be 12.0V to 14.5V). Check if the alternator is overcharging the system (external over-voltage cause).

2. 2

   Inspect the ACM wiring harness and connectors for dirt, corrosion, bent pins, or loose connections that could cause intermittent voltage spikes.

3. 3

   Verify that the negative battery/ground supply to the ACM is secure and free of corrosion.

4. 4

   Use the Case IH Electronic Service Tool (EST) to clear the code. Run the engine and check if the code returns as ACTIVE. If external voltage is stable at 12V but the code returns, it indicates an internal module circuitry failure.

1. 1

   Disconnect Power

   Turn off the keyswitch and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Address Charging System (If Applicable)

   If diagnostic checks revealed that the alternator is outputting excessive voltage (triggering the high voltage code), replace the alternator or voltage regulator before replacing any modules.

3. 3

   Access the ACM

   Locate the Armrest Control Module (typically inside the cab armrest console) or the Aftertreatment Control Module (typically mounted near the engine/exhaust), depending on which ACM is throwing the code.

4. 4

   Replace the Module

   Disconnect the wiring harnesses from the faulty ACM. Remove the mounting hardware and extract the module. Install the replacement ACM and securely reconnect the harnesses.

5. 5

   Calibrate and Program

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST). You must flash the correct software dataset to the new ACM and perform any necessary calibrations (e.g., calibrating the armrest levers, EHR valves, or multi-function handle) for the system to operate normally.