What Are the Reasons Why a Diesel Vehicle Won't Shut Off?

[JudahFitz]

When starting a diesel vehicle, the key only drives the flywheel to rotate, causing the piston to move and compress for combustion, which in turn pushes the crankshaft to reciprocate. Unlike gasoline vehicles, which rely on the key to control spark plug ignition, the diesel engine's starter motor ignites the engine and then becomes irrelevant. Even if the key is turned off, the high-pressure fuel pump continues to supply fuel regularly, unaffected by the key being turned off. Here are the solutions: 1. Directly disconnect the fuel line switch: This mechanical fuel line switch may be located under the seat or on the lower left side of the steering wheel, as the placement varies by vehicle model, so it's impossible to specify an exact location. 2. Electronic fuel injection diesel engines: Similar to gasoline engines, the key must be in the 'on' position for the system to receive power. The ECU controls the fuel injectors to spray fuel. Therefore, turning off the key in such diesel engines stops the fuel injectors from working, effectively cutting off the fuel supply and allowing the engine to shut off.