New Holland DCU 19730 – DCU: Ignition ‘on’ signal K15 | digital input ignition ON not sensed during initialization | P2530 Ignition switch - plausibility error

During the machine's startup sequence, the control unit did not detect the digital 'Ignition ON' signal (designated as terminal K15). The module is awake and communicating, but the physical signal from the ignition switch is missing, out of range, or implausible, preventing normal initialization.

• T6
• T7.185
• T7.260
• T7.270
• T8.300
• T8.390
• T8010-T8050
• T9.390
• T9.670
• C227
• C232
• C238
• L213
• L218
• L225
• L228
• Magnum
• Steiger

1. 1

   Test the ignition switch output at the K15 terminal to ensure it provides a steady 12V signal when the key is turned to the 'ON' and 'RUN' positions.

2. 2

   Inspect the wiring harness between the ignition switch and the Dosing Control Unit (DCU) for open circuits, chafed wires, or shorts to ground on the K15 signal wire.

3. 3

   Check the main power relays and ECM/PCM power control circuits, as this fault is frequently accompanied by related main relay codes (DCU 19739, 19740, or 19741).

4. 4

   Inspect the DCU connectors (located near the DEF supply module) for water ingress, corrosion, or pushed-out pins that could block the K15 wake-up signal.

1. 1

   Disconnect Power

   Disconnect the negative battery cable before servicing the electrical system to prevent short circuits.

2. 2

   Access the Switch

   Remove the steering column covers or side console panels to access the rear of the ignition switch.

3. 3

   Inspect and Test

   Disconnect the ignition switch harness. Reconnect the battery temporarily and use a multimeter to verify that power is reaching the switch. Turn the switch to the 'ON' position and verify continuity/voltage output on the K15 pin.

4. 4

   Replace the Switch (If Faulty)

   If the switch fails to output a consistent signal in the 'ON' position, remove the retaining nut, extract the old switch, and install a new OEM ignition switch.

5. 5

   Trace the Circuit (If Switch is Good)

   If the switch tests perfectly, trace the K15 wire from the dash down to the DCU. Repair any broken wires or clean any corroded harness connectors.

6. 6

   Clear Codes

   Reassemble the panels, reconnect the battery, and use a New Holland Electronic Service Tool (EST) to clear the DCU 19730 / P2530 fault codes. Cycle the key to verify the code does not return during initialization.