Engine Stop Solenoid Not Responding to Controller

Common Symptoms

• COMMANDER controller display shows fault code 15 and activates the alarm LED
• Engine continues running after you press STOP or after a commanded shutdown sequence
• Engine does not shut down at end of auto cool-down cycle
• Tower remains powered even though the panel shows a STOP command was sent
• Repeated fault code 15 appears every time engine is cycled OFF
• Engine shuts down immediately and will not restart, or shuts down unexpectedly mid-operation
• Visible burn smell near the injection pump or solenoid wiring harness on the Kubota block

Probable Causes (Ranked by Likelihood)

• Stop solenoid coil burned out or open-circuit -- coil winding has failed internally and draws no current Very Likely
• Broken, corroded, or chafed wiring between the COMMANDER controller and the solenoid connector on the Kubota fuel pump Very Likely
• Solenoid plunger mechanically stuck in the open (run) or closed (stop) position due to debris or corrosion Likely
• Solenoid connector pins backed out, corroded, or not fully seated at the fuel injection pump harness plug Likely
• COMMANDER controller output driver for solenoid circuit failed -- no 12 V DC signal leaving the controller terminal Possible
• Blown fuse or failed relay on the solenoid control circuit inside the control enclosure Possible
• Low battery or poor ground causing insufficient voltage to pull solenoid in fully Less Likely

Step-by-Step Diagnostic Procedure

1. Start safe. Press STOP on the panel and confirm the engine state. Note whether the engine keeps running or cuts immediately. Both conditions point to fault code 15 but from opposite solenoid failure modes -- stuck open means engine won't stop, stuck closed means engine won't run.

2. Locate the stop solenoid on the Kubota injection pump. It is a small cylindrical coil with a two-wire connector, usually mounted on the side or top of the pump body. Inspect the connector for backed-out pins, cracked insulation, green corrosion, or heat damage.

3. Disconnect the solenoid connector. Set your multimeter to resistance (ohms). Measure across the solenoid coil terminals. A healthy Kubota stop solenoid reads roughly 6 to 12 ohms depending on model. An open circuit reading (OL or infinity) means the coil is burned and the solenoid must be replaced.

4. With the connector still disconnected and the panel in the STOP position, set your multimeter to DC volts. Back-probe the harness side of the connector (not the solenoid side) and check for 12 V DC between the signal wire and chassis ground. Then switch the panel to RUN or AUTO. The voltage should switch states -- 12 V DC energized in RUN, near 0 V in STOP, or the inverse depending on solenoid type (energize-to-run vs. energize-to-stop). No voltage change in either state points to the COMMANDER controller output or a broken wire upstream.

5. Trace the solenoid wiring from the injection pump back to the control enclosure. Look for spots where the loom passes near hot exhaust components, sharp metal edges, or pinch points in the mast base. A chafed wire grounding against the frame can cause intermittent fault 15 that clears and returns with vibration.

6. Check the control enclosure fuse block and any relay associated with the solenoid circuit. Refer to the wiring diagram on the inside of the enclosure door. Pull the relevant fuse and inspect for a blown element. Swap the relay with an identical relay in the panel if one is present, then cycle the engine again.

7. If wiring, fuse, relay, and solenoid coil all check out but the COMMANDER controller still throws code 15, the problem is inside the controller output driver. At this point you need a replacement COMMANDER controller board or Allmand factory support. This is an advanced repair -- call your dealer or Allmand tech support at 1-800-562-1373.

8. After replacing the solenoid or repairing wiring, clear the fault on the COMMANDER display, cycle the panel from OFF to AUTO or MANUAL, confirm the engine starts and stops cleanly two or three times before returning the unit to service.

Frequently Asked Questions