What are the reasons why a car cannot be turned off?
2 Answers
The reason why a car cannot be turned off is likely due to damage inside the ignition switch. The ignition switch has ACC, ON, and START positions. Turning to ACC powers the car's electrical equipment; ON powers the ABS (Anti-lock Braking System), AIRBAG (airbag), fuel pump, and ECU power supply, among others; while START is for ignition. Solutions for not being able to turn off the car are as follows: 1. Directly disconnect the fuel line switch. This mechanical fuel line switch varies in location depending on the car model—some are under the seat, while others are on the lower left side of the steering wheel. 2. For electronically controlled diesel engines, similar to car keys, they only power on when in the ON position, with the ECU controlling the fuel injectors to spray fuel. Therefore, turning off the key for such diesel engines stops the fuel injectors, effectively cutting off the fuel supply.
I've seen many cases where a car won't shut off. The most common issue is a faulty ignition switch—worn or stuck internal contacts prevent the circuit from breaking, so the engine keeps running even after turning the key. Relays often fail too; if stuck in the "on" position, the power supply won’t cut off. Electrical shorts are another possibility, such as damaged wiring allowing continuous current flow. Anti-theft system malfunctions can cause the ECU to ignore shutdown signals, or the engine control module itself may be defective. Start troubleshooting with simple steps: check the fuse box for blown fuses and try turning the key repeatedly to see if it resolves. If not, seek professional repair immediately—prolonged operation risks engine damage or fire hazards, especially if ignored while driving.
