Case IH 17488 (F-522008-31) - ECU – DCU (Dosing Control Unit): DEF/AdBlue reverting pump driver circuit short to ground failure

The electrical circuit responsible for controlling the reverting valve/pump (which purges DEF from the lines back into the tank to prevent freezing) has shorted to ground.

• VESTRUM CVX
• Magnum Series (235–340, 315)
• Steiger Series
• Puma Series
• Axial-Flow Combines (7230, 7240, 7250, 8250, 9250)

1. 1

   Inspect the main frame harness connecting the DCU to the Urea Fluid Supply Module for chafing, bare wires, or pinched areas that could cause a short to ground.

2. 2

   Disconnect the DEF supply module and check the pins for corrosion or DEF fluid intrusion, which is highly conductive and can cause shorts.

3. 3

   Turn on the ignition switch without starting the engine. Clear the DTC with a diagnostic scan tool and observe if the code (or related codes like P20C9) returns immediately.

1. 1

   Turn off the ignition switch and disconnect the battery.

2. 2

   Locate the Urea Fluid Supply Module (DEF Dosing Pump).

3. 3

   Disconnect the electrical harness and DEF fluid lines from the module.

   Note: Be prepared to catch residual DEF fluid.

4. 4

   Remove the faulty Urea Fluid Supply Module / DCU assembly.

   Refer to the OEM manual section "Removal of DEF Supply Module".

5. 5

   Install the new DEF Supply Module.

   Refer to "Installation of DEF Supply Module".

6. 6

   Reconnect the fluid lines and electrical harness.

7. 7

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

8. 8

   Run the system to verify the code does not return and that the reverting pump operates correctly during the purge cycle.