New Holland ENG 3145 – Engine Control Module (ECM / EDC - Electronic Diesel Control): Terminal 15 - No Signal

The control module is failing to detect 12-volt power on the switched ignition circuit when it expects to, or the signal was unexpectedly lost while the engine was running. This usually points to a failure in the ignition switch, a faulty main power relay, a blown fuse, or a break in the wiring harness.

• T7 Series
• T8 Series
• B90B
• B110B
• B115B Loader Backhoes
• Magnum 235–340 (Series 4)

1. 1

   Check the main cab and engine power distribution boxes for blown fuses related to the ignition circuit, ECU power, or accessory relays.

2. 2

   Locate the main ignition/power relay and swap it with a known good relay of the same type (like the horn or light relay) to see if the fault clears.

3. 3

   Test the ignition switch for continuity and ensure it is successfully outputting battery voltage (approx. 12V) to the Terminal 15 circuit when turned to the ON position.

4. 4

   Trace the wiring from the ignition switch and relay to the Engine ECU. Inspect for chafed wires, broken connections, or corrosion at the ECU harness connectors.

5. 5

   Measure the voltage at the Terminal 15 pin on the ECU connector with the key ON to verify power is actually reaching the module.

1. 1

   Disconnect Power

   Always disconnect the negative battery cable before performing electrical repairs to prevent short circuits.

2. 2

   Address Fuses

   If a fuse was blown, replace it with one of the exact same amperage. If it blows again immediately upon turning the key, you must locate and repair a short-to-ground in the Terminal 15 wiring harness before proceeding.

3. 3

   Replace the Relay

   If the main ignition relay failed the swap test, pull the old relay from the block and plug in a replacement.

4. 4

   Replace the Ignition Switch

   If the switch failed the continuity test, remove the steering column/dash trim, disconnect the switch harness, unthread the retaining nut, and install a new OEM ignition switch.

5. 5

   Repair Wiring

   If the harness is damaged (open circuit or short), cut out the damaged section, splice and solder the wires, seal with heat-shrink tubing, and secure the harness away from heat sources or pinch points.

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a CNH diagnostic tool (EST) to clear the ENG 3145 fault code. Start the machine to verify the code does not return.