Case IH 19103 (F-519294-03) - ECU – DEF Supply Module: Urea/DEF Supply Module heater actuator power stage has a short circuit to the battery

The Heater Control Unit (HCU) or the internal driver circuit that supplies power to the Diesel Exhaust Fluid (DEF) supply module heater is detecting a direct short to 12V battery voltage. This prevents the system from properly heating the DEF fluid, which is required to prevent freezing in cold temperatures.

• VESTRUM CVX
• Magnum (180-370)
• Steiger (350-600)
• Puma (130-215)
• Maxxum (110-140)
• Farmall series
• 5130
• 6130
• 7130
• 7230
• 8230
• 9230
• Patriot 4430
• Titan series
• Farmlift series
• SV/TR skid steers

1. 1

   Inspect the wiring harness connecting the DEF Supply Module to the DEF tank heater and the HCU for any rubbed, chafed, or melted wires that could cause a short to battery voltage.

2. 2

   Disconnect the DEF Supply Module and use a multimeter to check the heater driver circuit pins for a short to 12V power.

3. 3

   Check the DEF heater control relay and the tank heating valve to ensure they are operating normally and are not stuck open or internally shorted.

4. 4

   Verify the resistance of the DEF supply module heater element to ensure the internal heater itself has not failed and shorted out.

1. 1

   Turn off the ignition switch and disconnect the machine's battery to prevent electrical damage.

2. 2

   Locate the DEF Supply Module (usually mounted near the DEF tank).

3. 3

   Disconnect the main wiring harness from the DEF Supply Module and inspect the connector pins for corrosion, moisture, or damage.

4. 4

   Test the harness side of the connector with a multimeter.

   If a short to battery voltage is found in the wiring, trace the harness back to the HCU/relay and repair or replace the damaged section of the wiring harness.

5. 5

   If the wiring harness tests good, the short circuit is internal to the DEF Supply Module's heater driver or the heater element itself.

6. 6

   Replace the DEF Supply Module (or the specific DEF Heater Control Unit relay if isolated).

7. 7

   Reconnect the battery, turn on the ignition, and use a diagnostic scan tool to clear the fault codes.

8. 8

   Run an SCR system test or allow the machine to run to verify the code does not return.