Case IH 13005 – UCM (Universal Control Module) / VCM (Vehicle Control Module): Reference voltage 5VREF3 - voltage too low

This code indicates that the 5-volt reference circuit #3 (5VREF3) has dropped below its normal operating range. This typically means there is a short to ground in the wiring harness, a sensor has failed internally and is pulling the voltage down, or the control module itself has an internal power supply failure.

• MAXXUM T4E
• Puma
• Magnum
• Maxxum
• Steiger
• Optum
• SR series
• SV series
• TR series
• TV series
• L-series
• T7
• T8
• T9
• CVT
• Profi

1. 1

   Sensor Isolation Test: Identify which sensors are powered by the 5VREF3 circuit and disconnect them one at a time. If the fault code changes to 13006 (High) or the 5V reference voltage returns to normal, the disconnected sensor is internally shorted.

2. 2

   Harness Inspection: If unplugging sensors does not clear the short, inspect the wiring harness between the UCM and the sensors for chafing, pinched wires, or melted insulation.

3. 3

   UCM Output Test: Disconnect the harness directly at the UCM and measure the voltage at the 5VREF3 output pin. If the module fails to output 5 volts with nothing attached, the UCM has an internal failure.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground before performing electrical repairs.

2. 2

   Repair Wiring

   If a short to ground was found in the harness, cut out the damaged section of wire. Splice in a new section of wire using OEM-approved methods (weather-proof heat shrink butt connectors or soldering with marine-grade heat shrink).

3. 3

   Replace Sensor

   If a sensor was pulling the voltage down, unbolt the faulty sensor, install the replacement, and plug it into the harness.

4. 4

   Replace UCM

   If the UCM failed the output test, remove the module and install a new one. Note: A new UCM will require dealer programming and calibration using the CNH Electronic Service Tool (EST).

5. 5

   Clear and Verify

   Reconnect the battery, turn the key on, and use the diagnostic display or EST to clear the stored 13005 fault code. Operate the machine to verify the code does not return.