New Holland ENG 3350 – Engine Control Module (ECM): Crank Input: Terminal 50 - Always On

The engine controller is detecting a continuous 12-volt signal on the crank input pin (Terminal 50), even when the ignition key is in the 'OFF' or 'RUN' positions. The system expects to see voltage on this circuit only when the operator is actively holding the key in the 'START' (cranking) position.

• L218
• L220
• SR175
• B90B
• B100B
• B110B
• T7 series
• T8 series
• CR series Tier 4A
• CX series Tier 4A

1. 1

   Ignition Switch Test: Disconnect the ignition switch and use a multimeter to test for continuity. Ensure that power is only routed to the Terminal 50 output pin when the key is physically turned to the 'START' position. If there is continuity in the 'RUN' position, the switch is internally shorted.

2. 2

   Starter Relay Test: Locate the starter relay in the fuse/relay box. Remove it and test for a stuck-closed internal contact (welded contacts). You can swap it with a known good relay of the same type to see if the continuous crank signal disappears.

3. 3

   Wiring Harness Inspection: Trace the Terminal 50 wire from the ignition switch to the starter relay, the starter solenoid, and the ECM. Look for chafed insulation, melted wires, or pinched harnesses that could be shorting the circuit to a constant 12V battery source (Short to B+).

4. 4

   Starter Solenoid Check: Ensure the starter solenoid is not internally shorted or backfeeding voltage to the ECM.

1. 1

   Disconnect Power

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent accidental engine cranking or electrical shorts during the repair.

2. 2

   Isolate the Fault

   Based on your diagnostic checks, identify whether the fault lies in the ignition switch, the starter relay, or the wiring harness.

3. 3

   Replace the Faulty Component

   If the ignition switch is faulty: Remove the dash console panel, unplug the wiring harness connector from the back of the switch, unscrew the retaining nut on the front of the dash, and install a new ignition switch. If the starter relay is faulty: Pull the defective relay from the power distribution center and plug in a new replacement relay. If the wiring is shorted: Cut out the damaged/melted section of the wire, solder in a new section of the same gauge wire, and seal the repair with heat-shrink tubing to prevent moisture intrusion.

4. 4

   Reassemble

   Reinstall any removed dash panels and reconnect the negative battery cable.

5. 5

   Test and Clear Codes

   Turn the key to the 'RUN' position and verify the starter does not engage prematurely. Start the engine normally. Use a diagnostic scan tool (like the CNH Electronic Service Tool) to clear the inactive ENG 3350 fault code from the ECM.