Case IH 3280 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC) / module A-095: 12V sensor supply 1 voltage is too high

The control module monitors the 12-volt sensor supply circuits, and this code triggers when the voltage on the "Supply 1" circuit exceeds the maximum allowable threshold.

• Steiger T4B
• Case IH Puma
• Magnum (e.g., 235–340 Series 4)
• Steiger models
• 240 Series Axial-Flow Combines (including models 7230, 8230, and 9230)

1. 1

   Verify that the tractor's battery is not currently connected to an external power supply, battery charger, or jump-starter

2. 2

   Test the machine's battery voltage while running to ensure the alternator voltage regulator has not failed (which would cause excessive system-wide voltage)

3. 3

   Inspect the wiring harness between the EDC and the sensors on the 12V Supply 1 circuit for chafed wires shorting to a higher voltage source

4. 4

   Check connected sensors on the 12V Supply 1 circuit for internal shorts back-feeding voltage into the supply line

1. 1

   Verify the Fault

   Use the Case IH Electronic Service Tool (EST) to verify if the fault code is currently active. If it is inactive, the issue may be an intermittent wiring short.

2. 2

   Isolate the Circuit

   Disconnect the sensors powered by the 12V Supply 1 circuit one at a time. If the voltage returns to normal (and the active code changes/clears) upon disconnecting a specific sensor, that sensor has an internal short and must be replaced.

3. 3

   Test the Harness

   If the sensors are fine, use a multimeter to test connector X-917 (specifically pin 84) and the associated sensor connectors for a short to battery voltage. Repair the wiring harness if a short is found.

4. 4

   Replace the ECU/EDC

   If the battery voltage is normal, the wiring harness is intact, and no sensors are shorted, the A-095 ECU (EDC) has suffered an internal electrical failure and is outputting excessive voltage. The ECU must be replaced and reprogrammed by a dealer.