Case IH 13004 – Universal Controller (UCM) / XCM: Reference voltage 5VREF2 - voltage too high

The 5-volt reference circuit #2 (5VREF2) is experiencing a voltage higher than its normal 5V operating range, typically indicating a short to a 12V power source (battery voltage) or an internal failure within the controller.

• MAXXUM T4E
• Puma Series (130, 140, 145, 160, 210)
• Magnum Series (225, 335, 380)
• Steiger Series (500)
• Axial-Flow Series (7230, 8230, 9230)
• Planters utilizing Pro 1200 display and Planter UCM

1. 1

   Perform a sensor isolation test by disconnecting the sensors on the 5VREF2 circuit one by one. If the voltage drops back to normal (or changes to code 13003), the disconnected sensor is internally shorted to 12V.

2. 2

   Inspect the wiring harness for chafing, melting, or pinch points. Look for areas where a bare 5V reference wire could be touching a bare 12V supply wire.

3. 3

   Check the UCM connectors (e.g., Connector X-950 pin 03, or CN1-A03 depending on model). Ensure the pins are not damaged, bent, or corroded, and that the connection is secure.

4. 4

   Test the voltage directly at the UCM 5VREF2 output pin with all sensors disconnected and harness verified. If it outputs significantly more than 5 volts, the UCM has an internal fault.

1. 1

   Identify Sensors

   Consult your specific machine's electrical schematic to identify every sensor powered by the 5VREF2 circuit.

2. 2

   Inspect and Repair Wiring

   Trace the wiring harness routing to these sensors. Repair or replace any damaged sections of the wiring harness where a short to 12V is found.

3. 3

   Replace Faulty Sensor

   If the sensor isolation test identified a specific sensor that is back-feeding voltage, replace that sensor.

4. 4

   Replace the UCM

   If the harness is intact and the sensors are good, but the UCM is internally shorted and outputting excessive voltage, replace the Universal Controller Module.

5. 5

   Clear Codes and Calibrate

   After replacing the faulty component, clear the stored fault codes via the diagnostic 'H menu' (specifically the 'HC - Clear all stored fault codes' menu) or using an Electronic Service Tool (EST). Verify the system functions normally and the code does not return.