Case IH 702-03 - UCM – UCM: Scraper (auto aux) input 2 voltage high

The control module is detecting a voltage signal on the input 2 circuit for the scraper's automatic auxiliary function that is higher than the expected normal operational range. This condition typically points to a short-to-power in the wiring harness, an open circuit, or a failed input sensor/switch.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series
• Case IH Steiger AFS Connect Series

1. 1

   Visually inspect the wiring harness running from the UCM to the scraper auto auxiliary input 2 connection for chafed wires, pinched lines, or exposed copper that could cause a short to a high-voltage source.

2. 2

   Disconnect the multi-pin OEM connectors at the UCM and the scraper auxiliary input and inspect for moisture, corrosion, or bent pins.

3. 3

   Use a multimeter to measure the voltage at the input 2 sensor/switch to verify if the sensor is internally shorted and sending a constant high voltage back to the UCM.

4. 4

   Verify that the UCM is running the latest software version (e.g., 51690149 or 51507814) to rule out a software glitch causing false high-voltage readings.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical spikes during the repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short-to-power or a broken wire in the scraper auto aux circuit, splice and repair the damaged section using weather-sealed connectors, or replace the affected harness section.

3. 3

   Replace Sensor/Switch

   If the wiring is intact but the input sensor/switch is outputting an out-of-range high voltage, remove and replace the faulty sensor.

4. 4

   Replace the UCM (If Necessary)

   If the wiring and sensors test perfectly but the UCM continues to read a high voltage internally, the UCM itself has failed. Unbolt the controller from its mounting bracket, disconnect the multi-pin connectors, and install a new OEM UCM.

5. 5

   Reassembly and Clearing Codes

   Reconnect the battery. Connect a CNH Electronic Service Tool (EST) to the machine's diagnostic port, clear the 702-03 fault code, and cycle the scraper auxiliary functions to verify the repair.