Case IH 2175 (518851.03) - DEC – UCM (Universal Control Module) or VCM (Vehicle Control Module): 12VH failed high

The control module is detecting a voltage at the '12VH' (High Side Supply) power input that is above the normal operating range. The 12VH circuit is receiving excessive voltage, either from an overcharging system or a short to battery power.

• MAXXUM T4E
• VESTRUM CVX
• 5088
• 6088
• 7088
• Early Riser series
• Titan Yieldtrac
• Steiger Tractors (350 to 600 HP)

1. 1

   Check Tractor Main Power (PWR) voltage level to verify if the alternator is overcharging the 12V system

2. 2

   Inspect the UCM enclosure for a failed power control relay that may be stuck closed or malfunctioning

3. 3

   Inspect the 12VH high-side supply wiring circuit for any chafing that could cause a short to a higher voltage source (battery positive)

4. 4

   Check the PWR fuses (such as fuse 1) inside the UCM enclosure to ensure they haven't blown due to the high voltage event

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent further electrical damage during diagnosis.

2. 2

   Test the Charging System

   Measure the alternator output at the battery terminals while the engine is running. If the voltage exceeds normal 12V system specifications (typically >15V), replace the alternator or voltage regulator.

3. 3

   Test/Replace the UCM Relay

   Locate the PWR control relay inside the UCM enclosure. Test the relay for proper operation. If it has failed or is sticking, replace the relay.

4. 4

   Repair Wiring Shorts

   Trace the 12VH wiring harness from the UCM to the power source. Repair or replace any sections of the harness that are shorted to battery voltage.

5. 5

   Clear Codes

   Reconnect the battery, power on the AFS display, and verify that the 12VH voltage is now reading within the normal parameters. Clear the fault code.