Case IH 19093 – DCU (Dosing Control Unit): Monitoring VDD11/ VDD25 voltage - Dosing valve/pump motor supply voltage VD25 high - 12 Volt supply for dosing module - Above upper limit

The system has detected that the 12-volt electrical supply (specifically the VD25 circuit) powering the Diesel Exhaust Fluid (DEF) dosing valve or pump motor is exceeding the maximum allowable voltage threshold. This typically points to a short circuit to battery voltage, a malfunctioning alternator overcharging the system, or an internal failure within the dosing module itself.

• Tier 4a
• Tier 4B
• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 225
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Magnum 370
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Puma 130
• Puma 145
• Puma 160
• Puma 170
• Puma 185
• Puma 200
• Puma 215
• Puma 230
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 135
• Maxxum 140
• Maxxum 145
• Maxxum 150
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Titan 3030
• Titan 3530
• Titan 4030
• Titan 4530
• Patriot 2240
• Patriot 4430
• Case Loader 521F
• Case Loader 621F
• Case Loader 1021F
• Case Loader 1121F
• Case Dozer 850M
• Case Dozer 1150M
• Case Dozer 1650M
• Case Dozer 2050M

1. 1

   Check System Voltage: Verify the battery voltage and test the alternator/charging system. An overcharging alternator can trigger high-voltage codes across multiple modules.

2. 2

   Inspect Wiring and Connectors: Inspect the wiring harness leading to the DCU and the dosing module. Look for rubbed or chafed wires that could be causing a short circuit to a higher voltage source (battery +).

3. 3

   Test DCU Supply Voltage: Check the voltage supply directly at the Dosing Control Unit pins.

4. 4

   Internal Failure Check: If the voltage supply to the DCU is correct and the wiring is intact, but the failure occurs repeatedly, the fault is an internal dosing module/DCU failure.

1. 1

   System Purge

   Turn off the ignition key and wait. Do not disconnect the battery immediately. The DEF system must complete its automatic purge cycle (which pulls fluid back into the tank to prevent freezing) before power is cut.

2. 2

   Disconnect Power

   Once the purge is complete, disconnect the machine's battery to prevent electrical shorts.

3. 3

   Relieve Pressure

   If required by the specific model's service manual, use a diagnostic scan tool to safely relieve any residual pressure in the DEF lines.

4. 4

   Disconnect Electricals

   Carefully unplug the electrical connector from the dosing module. Use the release tab and avoid pulling directly on the wires.

5. 5

   Disconnect DEF Lines

   Use a DEF-rated line wrench to loosen and remove the DEF supply and return lines. Have a clean rag or absorbent pad ready to catch any residual urea fluid.

6. 6

   Remove the Module

   Unbolt the dosing module from its mounting bracket and remove it from the machine.

7. 7

   Install New Module

   Mount the replacement dosing module and secure the bolts.

8. 8

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical connector.

9. 9

   Clear and Test

   Reconnect the battery, use a diagnostic tool to clear the 19093 / P0659 fault codes, and run the engine to prime the system and check for leaks.