Case IH 19262 – DCU: Tank heating Valve | Short circuit to battery

The control module has detected that the electrical circuit for the DEF (Diesel Exhaust Fluid / Reagent) tank heating valve is shorted to a high voltage source (the battery), preventing the valve from operating correctly.

• Tier 4a
• Tier 4b
• Magnum 235 - 340 (Series 4)
• STX Steiger tractors (350 to 600 HP)
• Puma series
• Farmall Tier 4B (Final) tractors (110A, 120A, 130A, 140A)
• Farmlift telescopic handlers (737 Stage IV)
• CX220E Excavators

1. 1

   Check the Coolant Control Valve (CCV) for physical leaks and ensure the coolant lines are properly connected.

2. 2

   Feel the coolant lines going to the DEF tank level unit; if warm when the system should be off, the valve may be mechanically stuck open.

3. 3

   Disconnect the wiring harness at the DEF tank heating valve and inspect connectors and terminals for damage, moisture, corrosion, or poor terminal tension.

4. 4

   With the ignition ON, measure the voltage at the harness connector to check for a constant 12V supply on the control circuit where there shouldn't be. Trace the wiring back to the DCU to locate any rubbed or chafed wires shorting to a 12V power source.

5. 5

   If the wiring is intact and shows no shorts, test the internal solenoid of the heating valve itself, as it has likely failed and shorted internally.

1. 1

   Prepare machine for service

   Park the machine on a level surface, turn off the engine, set the parking brake, and disconnect the battery isolator switch.

2. 2

   Locate the valve

   Locate the DEF/AdBlue heater coolant control valve near the DEF tank.

3. 3

   Pinch coolant lines

   Using hose-pinch pliers, carefully pinch off the rubber coolant lines connected to the valve to prevent excessive coolant loss. Note: Do not pinch hard plastic or metal lines, as this will damage them.

4. 4

   Place catch pan

   Place a catch pan underneath the valve to catch any residual engine coolant.

5. 5

   Disconnect electrical harness

   Disconnect the electrical wiring harness connector from the heater control valve.

6. 6

   Disconnect coolant lines

   Disconnect the coolant inlet line, coolant outlet line, and the bypass line from the valve.

7. 7

   Remove old valve

   Remove the retaining bolts (usually hex bolts) securing the coolant control valve to its mounting support bracket and remove the old valve.

8. 8

   Install new valve

   Position the new DEF tank heating valve on the bracket and secure it with the retaining bolts.

9. 9

   Reconnect coolant lines

   Reconnect the coolant inlet, outlet, and bypass lines.

10. 10

    Reconnect electrical harness

    Reconnect the electrical wiring harness.

11. 11

    Remove hose-pinch pliers

    Remove the hose-pinch pliers.

12. 12

    Top off coolant

    Top off the engine cooling system with the appropriate coolant to replace any lost fluid.

13. 13

    Test and verify

    Reconnect the battery, turn the ignition on, clear the fault codes using an Electronic Service Tool (EST) or scan tool, and run the machine to verify normal operation and check for leaks.