Case IH 19075 – DCU (Dosing Control Unit): Voltage supply 2 - tube heaters (UB2) electrical

Open Load or a Short circuit to Ground on the DEF/AdBlue Suction Line Heater Actuator powerstage. The system has detected that the electrical circuit responsible for heating the DEF suction tube (to prevent the diesel exhaust fluid from freezing) is either open or shorted low.

• Tier 4b
• Magnum series (235–340 Series 4)
• Puma series (210, 220, 235, 250, 260, 270)
• N-Series Loader Backhoes
• F-Series Wheel Loaders (721F, 821F, 921F)
• M-Series Dozers (850M, 1150M, 1650M, 2050M)

1. 1

   Visually inspect all connectors to ensure they are properly seated on the Denox module/DCU and that all DEF lines are in operable condition without visible physical damage or pinching.

2. 2

   Access and disconnect the DEF harness connector (often a 6-pin connector near the frame rail) on the heated DEF line harness. Measure the resistance of the DEF heater circuits on the DEF line side of the connector. The resistance should be around 5.5 ohms +/- 1 ohm at 69 degrees F (20 degrees C).

3. 3

   If the resistance of the heater itself is within spec, check the wiring harness between the DCU and the DEF suction line heater for a short circuit to ground or an open wire.

4. 4

   If the resistance of the heater is out of specification (open or shorted), the DEF line assembly must be replaced.

1. 1

   Preparation

   Park the vehicle on a level, solid surface. Turn the ignition switch to the OFF (LOCK) position, remove the key, apply the parking brake, and chock the wheels.

2. 2

   Cool Down

   WARNING: NEVER remove coolant lines until the engine has cooled off completely. Failure to allow the engine to cool off may result in serious coolant burn injuries.

3. 3

   Drain Fluids

   If your machine utilizes SCR coolant lines routed alongside the DEF lines, place a drain bucket under the coolant lines. Remove the coolant supply line from the coolant cut valve hose and the return line, then discard the drained coolant.

4. 4

   Disconnect Electricals

   On the driver's side/frame rail, disconnect the DEF harness wire connector to the DCU harness.

5. 5

   Disconnect DEF Lines

   Disconnect the DEF line connection from the DEF injector and the DCU.

6. 6

   Remove Retainers

   Remove the harness clips from the brackets. Remove the retainer clips holding the DEF line assembly along the frame rail to free the line.

7. 7

   Install New Part

   Route the new heated DEF suction line assembly into place. Secure all retainer clips along the frame rail and frame brackets.

8. 8

   Reconnect

   Reconnect the DEF line to the injector and the DCU. Reconnect the electrical harness to the DCU. Reattach any coolant lines that were removed and refill the coolant system.

9. 9

   Clear Codes

   Turn the battery disconnect switch back on, clear the fault codes from the DCU, and run the machine to verify the code does not return and the heater operates correctly.