Check the battery: Before assuming the starter motor is the problem, check the battery. Make sure it’s fully charged and has no corrosion on the terminals. Using a battery with a small capacity or a poor state of charge will make the starter fail to reach the designed output power.
Listen for sounds: When you turn the key, listen for sounds coming from the engine. Listen to whether the starter gear pops up and the sound of running to confirm whether the electromagnetic switch and the armature are in action.And listen to whether the pop-up and running sound of the starter gear is normal, including: abnormal sound of flywheel damage, starter gear and internal damage; high noise during operation; sound of the starter not stopping working and rotating with the engine.
Inspect the wiring and voltage of the starter: Confirm that the S-terminal plug connecting the starter to the car starter switch has been inserted in place. Measure the voltage of terminal B of the starter, which should be consistent with the voltage of the battery.
Test the battery terminals for looseness and poor contact, check for broken lines and grounding conditions:
Poor wiring harness and wiring (wire harness grounding, wiring harness short circuit, loose and rusted wiring parts), the voltage applied to both ends of the starter is insufficient, and the starter works under low voltage for a long time.
Check the ignition key and protection relay for poor return and stuck conditions:When the ignition key returns automatically, measure the S terminal of the starter. If there is voltage at the S terminal, please check the ignition key and the protection relay. This situation will cause the starter to still be energized after the engine is started, so that the starter can not be disconnected from the flywheel of the engine, and the starter gear will be driven by the flywheel to rotate at high speed passively,and the starter gear will be damaged if it is energized for a long time.
Check the oil viscosity: The engine is locked and the viscosity of the engine oil is high, which will cause a large starting resistance.
Seek professional help: If you’re unsure about any of the steps or don’t have the necessary tools, it’s best to seek professional help. A mechanic can diagnose the problem and recommend the best course of action.