Case IH DCU19730 – DCU: Ignition ON Signal Not Sensed During Initialization

The Dosing Control Unit (DCU) failed to detect the 'Ignition ON' signal during its initialization process. This indicates an underlying issue within the ignition switch's 'run' position circuit. The DCU, which manages the Selective Catalytic Reduction (SCR) system, expects a voltage signal confirming the ignition is active. If this signal is missing, implausible, or unrecognized by the control unit during startup, the fault code is logged.

• 621F
• 721F
• 821F
• 921F
• 1021F
• 1121F

1. 1

   Verify the presence of active and stored fault codes to confirm that DCU19730 / P2530 is present

2. 2

   Visually inspect the ignition switch, its electrical connector, and the wiring harness leading to the Dosing Control Unit for signs of damage, corrosion, loose connections, or chafed wires

3. 3

   Check for other active fault codes, particularly related to main relays or communication errors, which could point to a broader electrical issue

4. 4

   Test the ignition switch using a multimeter to verify it is sending the correct voltage on the 'run' circuit when the key is in the 'ON' position

5. 5

   Check for low system voltage by ensuring the battery is fully charged and the charging system is functioning correctly

1. 1

   Repair wiring and connectors

   If visual inspection reveals any damaged wires or corroded connectors between the ignition switch and the DCU, repair or replace them as necessary. Ensure all connections are clean and secure.

2. 2

   Test ignition circuit continuity

   Trace the ignition 'ON' signal wire from the ignition switch to the DCU using a wiring diagram. Check for continuity and ensure there are no shorts to ground or open circuits.

3. 3

   Replace the ignition switch

   If the ignition switch is found to be faulty during multimeter testing (failing to send correct voltage on the 'run' circuit), replace the switch.

4. 4

   Check the main relay

   Inspect and test the main relay that supplies power to the engine and emissions control systems. This is especially relevant if associated main relay error codes (19739, 19740, 19741) are present.

5. 5

   Inspect and replace the DCU

   If the ignition switch and wiring are confirmed to be in good working order, inspect the DCU's connectors for damage or corrosion. If an internal fault is suspected, replace the Dosing Control Unit. Note that a replacement DCU may need to be programmed to the machine.