What are the causes of a starter motor not turning?

[VanCollin]

Fault reasons for a starter motor not turning: 1. Battery depletion, broken connecting wires, or loose terminals; 2. Severe burning of the starter relay contacts or open circuit in its coil; 3. Severe burning of the starter solenoid switch contacts or open circuit in its pull-in coil; 4. Open or short circuit in the internal windings of the starter DC motor; 5. Internal faults in the starter, such as a bent armature shaft, severely burned commutator, excessive brush wear, brushes stuck in the brush holder, or weak brush spring pressure. The starter is a machine that drives the engine to operate, converting the electrical energy from the battery into mechanical energy to rotate the engine flywheel and achieve engine start-up. If the starter malfunctions, the engine cannot start.

[MacWyatt]

I've encountered a dead battery several times, which is the most common cause of starter failure. Especially in winter when temperatures drop, batteries are more prone to issues. You can first try turning on the headlights - if they appear dim or don't light up at all, it's almost certainly a battery problem. Aside from battery aging, it could also be a faulty relay or blown starter fuse, which are clearly labeled in the fuse box. Loose wiring is another potential culprit, and dirty battery terminals causing poor contact can have the same effect. My suggestion is to use jumper cables for emergency starting. If you really get stuck in this situation, directly telling roadside assistance 'dead battery' when calling for help is the most efficient approach.

[LaLucy]

When I first started learning car repair, my mentor taught me the sequence for troubleshooting starter motor failures. First, listen carefully for a 'click' sound when starting the engine. If there's a sound but the engine doesn't turn over, it's likely due to insufficient battery power. If there's no sound at all, check the ignition switch and starter relay, as faults in the starter motor itself are relatively rare. I've also encountered uncommon situations—a faulty gear position sensor in an automatic transmission car can cause the system to mistakenly think it's not in P (Park) mode, rendering the key turn ineffective. In some cars, a jammed steering column lock can also affect the starting circuit, requiring repeated wiggling of the steering wheel to unlock it.

[ElainaMarie]

When my old car had starting issues, I figured out that the first thing to check is whether the battery voltage is below 12V. Borrowing a multimeter to measure the voltage is quite convenient. If the voltage is normal, then you need to follow up by checking: when turning the key to the START position, observe if the dashboard loses power—this indicates a loose main power line. The starter relay is located in the engine compartment fuse box; tapping it lightly might temporarily restore contact. Last time, my car's issue was worn-out starter brushes, characterized by hearing the relay click but the starter showing no movement at all. Cars with aftermarket anti-theft devices should also be checked for wiring conflicts.

[Stacy]

Last week, my neighbor's aunt couldn't start her car. When I checked it, I found several key points. Starter failure generally falls into two categories: battery issues or control circuit faults. For battery problems, check if the terminals are oxidized or whitened—tightening them with a wrench might solve it. For control circuit issues, start from the ignition switch, then check the fuse, relay, and finally the starter. The most practical method is to have someone turn the key while you feel the starter relay casing with your hand. If there's noticeable vibration, it means the control signal is normal, and the problem lies with the starter itself. Older cars with aging wiring often have issues in the wiring harness under the steering wheel.

[McJosie]

After a decade of car repairs, I've summarized the 'Four-Step Troubleshooting Method' for starting failures. First trick: Check the dashboard - when the key is turned to the ON position, does the battery light not come on? Immediately check the main fuse. Second trick: Listen for sounds - is there a relay 'clicking' sound when starting? If not, it means the control circuit is broken. Third trick: Test voltage - use a screwdriver to bridge the thick terminal on the starter with the solenoid terminal; if sparks fly, it means the motor is working. Finally, check the mechanical parts: for manual transmission cars, don't forget to see if the clutch switch is stuck. Last time I encountered loose battery cables that were hot to the touch!