Common Issues of Automotive Starting System (Case Study)

Vehicles are important transportation facilities in our daily lives. With the increase in the number of cars, engine issues can be big trouble for us. Starting system failure is one of the most common ones among these failures. How to solve those problems has become one of the inevitable concerns in repair and maintenance.

1. Components

2. Problems

    2.1 Dead starter

    2.2 Abnormal working starter

    2.3 Inappropriate idling

3. Case study

4. Conclusion

1. Components

The automotive starting system is mainly composed of a high-powered battery, a starter motor, an ignition switch and a starting relay.

Speaking of the starting system, the electrical energy in the car battery must be converted into mechanical energy if the car is to start smoothly. Then the resulting torque is transferred to the engine flywheel. It controls the engine.

The ignition switch is responsible for connecting the switch circuit so that the solenoid switch can work continuously and steadily.

The starting relay is responsible for controlling the high current through the small current to avoid the high current going straight through the ignition switch and affecting the service life of the ignition switch.

2. Problems

There are three main issues in the starting system: dead starter, abnormal working starter and inappropriate idling.

2.1 Dead starter


The dead starter can't run at all after turning on the switch. There is no operation of the component.


●  The power supply does not work correctly when the car starts

When this problem occurs, it is often due to a lack of power in the car battery, poor contact between the battery lead and the terminals, a broken battery lead or an internal battery fault.

●  Starter motor failure

Electric motor or solenoid switch failure

●  Fault in control wire

Faulty ignition switch, fuse, starter relay or wiring disconnection


●  Check if the issue is in battery

The battery can be checked by a high rate discharge meter. The power supply can also be checked for proper operation by driving the headlights or pressing the horn, depending on the intensity of the light and the sound volume.

Check to see if there are any loose connections in the starter circuit that are not secure or stable. Shake the car slightly by hand.

If you find that the connection is not secure or it wobbles when you touch it, you can confirm that the wiring in this position is not securely connected.

If it is confirmed that there are no problems with the connection, it is necessary to start rechecking the position of the car battery.

●  Inspection of the position of starter

First of all, the circuit at the beginning of the car starter should be connected to a well-insulated device. When the circuit is still not working after the connection, it is possible to confirm that there is a problem with the car motor. If the starter is idling after the test finishes, we can try the subsequent test of the equipment.

If the starter still does not work properly after the solenoid switch has been connected to the starter power supply with a well-insulated device, the starter switch is faulty. It must be removed by means of an elimination procedure.

If the starter normally works after switching on the wiring, it can be confirmed that the reason for the car not starting is a problem with the relay or the relevant wiring.

●  Check if the issue is in the control circuit

Test the fuse with the multimeter in the beeping position. If it does not work, the fault is there. If it is on, the fault is not in the fuse. We can proceed to the next check.

Test the starter relay coil for conduction. The ohmic class of the multimeter can test the coil of the relay. If the resistance value is infinity, the broken starting relay coil is the fault. If the resistance value is normal, carry out a dynamic test.

Test the starter relay switch for working condition. Connect the starter relay coil to the positive and negative terminals of the battery with two wires. Energize the coil and check if the switch closes by the multimeter simultaneously.

If it does not turn on properly after the test, we can say that the failure to start the car is due to the starter relay switch. If it turns on successfully, we can close and operate properly. Also, check the wiring of the other components to make sure that there is no short circuit.

2.2 Abnormal working starter


The drive gears in the system act normally when we start the car, but the starter speed does not reach the normal rotation level. There are problems with stalling.


Poor performance of the vehicle battery results in weak power. There is also a risk that the car power leads may have insufficient contact or robustness.

There is another situation: starter motor failure. A short circuit in the coil of the solenoid switch, dirty commutator, and badly worn brushes result in a softening of the spring, causing problems with the contact of the internal equipment.

Swelling or twisting the engine's armature shaft or a large shaft gap can be wrong. These issues lead to collision and friction between the rotor and stator. Over-tightened bearings lead to high resistance to rotation.

2.3 Inappropriate idling


The starter works, but the engine is dead.


This is due to the clutch being struck or broken, deformation of the fork or loosening of the linkage, problems with the travel between the starter drive gear and the flywheel ring, inability to move the drive gear flexibly, too little trip between the cores of the solenoid switch, significant wear or damage to the starter drive gear or the engine gear ring.


The idling speed of the starter is high. The drive gear and ring engage but still cannot drive the flywheel rotation. Only the machine noise can be heard, and there is no sound of gear collision. A slipping or broken freewheel usually causes this.

When the starter is idling, if you hear the sound of violent scraping of the gear teeth, the flywheel gear teeth, or the starter's drive gear is significantly worn.

As a result, you must promptly remove the starter and inspect it. Then you can replace the flywheel gear ring according to the specific situation.

If there is a slight rubbing sound when the starter is idling, it can be confirmed that the gears are not tightly engaged with the flywheel ring.

The solenoid switch can be switched on in advance, which means that the core travel is too short. The starter must be removed and adjusted accordingly.

3. Case study

A BMW can not start. It was taken to the repair shop for inspection.

If the car circuit is faulty, the starter will not work when the engine starts. At this point, we can determine where the fault point is by the trouble code or other information read by the detector.

The fault is much more complicated if the car starter works during the starting process, but the engine can not start. In this case, the fault may lie in the fuel system, the engine itself or the ignition system.

The mechanic tried to start the car, but it failed. After connecting the tester, he found an issue in the starter system control unit of the vehicle.

However, the battery power supply was normal. Therefore, he tried to clear the trouble codes that appeared. The code was removed, and the car started normally. The fault disappeared.

Information received by the control unit controls the starter. The vehicle can only start when the vehicle's control unit has received the vehicle's braking signal, the start-stop signal, the recognition signal to the remote control transmitter and the signal that the engine is running properly. If there is a problem with any of these, the vehicle will not start.

The mechanic judged that the fault was in the starter itself. He replaced the car starter, and the fault disappeared. The vehicle could start normally.

4. Conclusion

To sum up, when a problem occurs in the starting system, it should be confirmed in which aspect the fault is located by means of elimination, and then follow some fault-specific phenomena to determine where the fault is located and the faulty parts.

Lauritz Carolsfeld        April 07, 2022

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