Case IH 3253 – Engine Controller / ECU (ECU A-095): ECU internal failure - Voltage ratio in ADC monitoring

This fault indicates an internal hardware or software evaluation error within the Electronic Control Unit (ECU). Specifically, the ECU monitors the efficiency of its internal Analog to Digital Converter (ADC) using a voltage ratio conversion test. The controller counts each time the voltage ratio falls out of the desired/expected range. If this count exceeds 15 times, the fault code is logged.

• Farmall
• Steiger T4B
• Case IH 240 Series Axial-Flow Combines
• Case IH Magnum 235 - 340 (Series 4) Tractors
• Case IH / New Holland Skid Steer Loaders (SSL)
• Case IH / New Holland Compact Track Loaders (CTL)

1. 1

   Verify that the machine's battery power supply has not been connected to an external power supply (such as a jump box or external charger operating at an incorrect voltage)

2. 2

   Check the Engine Controller (ECU A-095) to ensure it is running the most up-to-date and appropriate software version

1. 1

   Isolate Power

   If an external power supply is currently connected to the tractor/machine, disconnect it immediately and test the system for normal operation. Voltage irregularities from external sources can trigger ADC monitoring faults.

2. 2

   Re-flash the ECU

   Connect your diagnostic service tool (e.g., EST) and check the ECU A-095 software. Re-flash the ECU with the latest software update if necessary.

3. 3

   Retest

   Cycle the key and operate the machine. If the fault is resolved: Return the machine to service. If the fault is not resolved: The internal ADC failure is a hard hardware fault, and the Engine Controller must be replaced.

4. 4

   Module Replacement

   Remove and replace the Engine Controller (ECU A-095).

5. 5

   Restore Parameters

   After replacement, you must use the appropriate service tool procedure to restore the engine's self-learning parameters and program the correct fuel injector codes into the new ECU.