Case IH 13006 – UCM (Universal Control Module): Reference voltage 5VREF3 - voltage too high

The control module is detecting a voltage on the 5VREF3 circuit that is significantly higher than the expected 5 volts. This is almost always caused by a short to power (the 5V wire is touching a 12V power source) or an internal failure within the control module's voltage regulator.

• MAXXUM T4E
• Magnum series
• Puma series
• Steiger series
• Maxxum series
• Axial-Flow Flagship series (7230, 8230, 9230, 7240, 8240, 9240, 7250, 8250, 9250)
• Early Riser 2000 Series
• SR series
• SV series
• TR series
• TV series

1. 1

   Disconnect the sensors that share the 5VREF3 circuit one at a time to check for an internal sensor short back-feeding voltage

2. 2

   Visually inspect the wiring harness for the 5VREF3 circuit for chafing, melted insulation, or pinch points shorting against a 12V supply wire

3. 3

   Inspect the UCM connectors and sensor connectors for moisture, corrosion, or bent pins that could bridge a 12V pin to the 5VREF3 pin

4. 4

   Disconnect the wiring harness from the UCM and measure the voltage directly at the 5VREF3 output pin to check for an internal UCM failure

1. 1

   Safely Prep the Machine

   Turn off the ignition and disconnect the negative battery cable to prevent accidental shorts during testing.

2. 2

   Access the UCM

   Locate the Universal Control Module (location varies heavily by machine; usually in the cab console, armrest, or main electrical bay).

3. 3

   Test the Circuit

   Reconnect the battery, turn the key to the ON position (engine off). Back-probe the 5VREF3 wire at the UCM connector with a multimeter.

4. 4

   Isolate the Short

   If the multimeter reads ~12V, begin unplugging sensors on that circuit. If unplugging a sensor fixes the voltage, replace that sensor. If all sensors are unplugged and the voltage is still high, disconnect the harness from the UCM.

5. 5

   Repair Wiring or Replace UCM

   Test the UCM pin directly. If it reads 5V, the short to 12V is in the wiring harness. Trace the harness and repair the shorted wires. If the bare UCM pin outputs high voltage, the UCM's internal 5V regulator is fried.

6. 6

   Replace the UCM (If faulty)

   Disconnect the battery, unplug the UCM connectors, unbolt the module, and install the replacement.

7. 7

   Flash and Calibrate

   Connect the Case IH Electronic Service Tool (EST) laptop to flash the module with the correct software payload for your specific machine's PIN/serial number, and then clear the 13006 fault code.