What Causes the Car Starter Motor to Not Respond?

[McAlejandro]

Here are the specific reasons why a car starter motor may not respond: 1. Severe wear of starter carbon brushes: The symptom during startup is weak cranking, where the crankshaft rotation is visibly slow through the belt and pulley. When the wear is extremely severe, the starter cannot rotate the crankshaft at all, producing only an electric current sound. 2. Fault in the starter control mechanism: Apart from the starter motor, the starter assembly includes an electromagnetic control mechanism. When this mechanism fails, the pinion gear cannot engage with the flywheel gear, preventing engine startup. The symptom is turning the ignition key and hearing only the high-speed rotation sound of the starter without the sound of the engine crankshaft flywheel operating. 3. Damage to the starter clutch: Typically, the starter operates at around 120r/min, while the engine idles at approximately 900r/min after starting. The clutch prevents the engine from driving the starter if the driver fails to release the key promptly after startup, keeping the pinion and flywheel gears engaged, which could lead to starter burnout.

[VanKate]

I've encountered the issue of the starter motor not responding several times, and there are quite a few possible causes. The most common one is a dead battery – if you forget to turn off the headlights or haven't driven the car for a long time, the battery voltage drops below 12 volts, making it unable to power the starter. Corrosion or looseness in the battery terminals can also cause poor contact, which can be fixed by cleaning them. The starter motor itself failing is also fairly common, often due to worn carbon brushes or a stuck solenoid switch. Additionally, a faulty ignition switch or a short circuit in the signal wire can disrupt the control system, like what happened with my old car when the wiring aged – turning the key did nothing. For automatic transmissions, you must be in P (Park), and for manual transmissions, you need to fully depress the clutch; otherwise, the computer will lock out the starter. If jump-starting doesn’t work, it’s best to take the car to a repair shop to check the wiring and starter motor, as forcing a start could damage components.