At present, most modern cars are electrical starting system, automotive circuit failure in the starting system has been very common. However, the reasons for the circuit failure of the vehicle starting system are very complex, and the failure occurs in many different parts, which brings us difficulties in the detection and diagnosis of the vehicle starting system. In order to further improve the diagnosis and troubleshooting of circuit failure ability, it is necessary to accurately grasp the starting system circuit diagram, so as to correct and troubleshoot the starting system faults, let's understand the car starting system faults analysis.

Automobile starting system components

In order to respond quickly to the failure of the car starting system, it is necessary to know the car’s starting system components. The starting system of automobile is made of the accumulator(battery), starter relay, ignition switch and starter motor.  In the starting system, any device is necessary, the car can start normally by these devices. The working principle of the starting system is very simple, first turn on the circuit equipment on the battery through the ignition switch, so that the battery quickly generates electrical energy, and then start the starter motor by the ignition switch. The battery's electrical energy converts into mechanical energy, and generates the energy needed to start the system.

1. Common circuit failure&analysis and troubleshooting 

when turn the ignition switch to the 'on' position, the starter motor does not work properly.

In this case, we troubleshoot the failure based on the specific conditions. Because there are many reasons why the starter motor does not work, failure of any part of the starting system will cause the starter motor failure. We generally summarize it as the following reasons. 

(1) The battery is insufficient in power, which cannot be converted into mechanical energy after starting the engine, unable to drive the operation of the starter motor.

(2) In the car starting system, there are problems with the wiring connection in some of the circuit units, such as poor contact, starter switch problem, the starter switch does not control the starter.

(3) It is also possible the relay failed in the starting system.

In the cause of the failure, it is necessary to troubleshoot the fault, so that the starting system can work normally as soon as possible.

The normal troubleshooting procedures are as follows:

First of all, check the battery. If the battery is low, it indicates that the failure of the starter may be caused by this reason. You can replace it with a new battery.

Second, test the circuit connection. Use wire connect the terminal of starter switch, if starter works normally, then connect the terminal of safety ring. If the starter can work normally, we can ascribe failure point on the relay circuit, checking and removing the malfunction.

Third, check the starter switch. Most of the switches in the starter are starter switches. In the long-term use, the starter switch may suffer from aging, wear and other faults. Therefore, a new starter switch can be replaced, then try to start engine again, if the engine start is normal, the fault can be eliminated. 

In addition, if the fault still can’t be removed after following the steps above, the starter motor is not running, then check whether any oxidation is on relay contact. If the contact gap is too larger, and hard to close, it will cause the circuit failure, you must carry on the corresponding adjustment of the relay contact clearance, make sure the starter motor works normally.

2. Starter motor failure analysis and troubleshooting

After starting the car, the engine starter can run, but it is obviously weak.

Symptom: switch on the starter switch, the starter operation is stuck or stagnant or slow. The starter is weak in operation, indicating that the load capacity is reduced and the actual output power is reduced.

The reasons for the failure are as follows:

A. Battery loss or short circuit fault reduces its power supply capacity.

B. The contact resistance of the main circuit starter has increased, resulting in the working current of the starter in decline. The reasons for the increase of contact resistance include: the wires leading from the battery to the starter motor are in poor condition and the wires aren’t fitted correctly. The contact between the starter solenoid switch and the contact plate is bad contact. Excessive wear of brush bar causes excessive reduction of brush spring pressure, which leads to poor conductivity of brush and commutator. 

C. Partial short-circuit of the magnetic field winding or armature winding reduces the output power of starter motor.

D. The starter motor ‘s bearing is damaged, resulting in excessive rotational resistance.

E. Too tight engine assembly or low working environment temperature may cause large starting torque, or the starter can't run.

Starter motor failure analysis and troubleshooting

A. The battery wire is a key component in the operation of the starter motor. Check whether the battery and the wiring connection are normal, and pay special attention to check whether the battery, starter and cable connector are in good contact. 

B. If the battery and wiring are in good condition, it indicates a fault with the starter. The cause of this fault is mostly caused by bad contact of battery or circuit. In the event of such a fault, the following routine elimination should be performed.

First of all, we should consider the environmental temperature factor when the car starting system fails. In low temperature and severe cold weather, the starter motor of the car starting system will also fail. This is reason why the low temperature weather will increase the resistance in the battery, and cause the friction resistance of the engine to increase, affecting the engine operation.

Next, inspect the starter, check whether the battery power is enough. If enough, check the starter switch, the terminal on the starter switch can be directly connected with a conductor. If the running speed of the starter is no changing, indicates the poor contact in circuit. If the starter runs at high speed, it indicates the starter switch has bad contact, it is necessary to troubleshoot the circuit to ensure wiring connection is unblocked. Check whether there is any sign of looseness at the connector of the starter motor. If necessary, replace the seriously corroded joint, and tighten the loose interface.

Third, if these parts are found to be free of problems through the above detection and troubleshooting, the possibility of the above faults can be basically eliminated. Then check the starter's bearing, if the bearing is bent or too tight, the faults we mentioned may also be caused.

3. The starter is running continuously

Compared with other faults, this kind of fault is easier to be solved. The problem is caused by the contact between the contact plate of solenoid switch and the two main circuit. When troubleshooting, pay attention to check whether the contact plate of the solenoid switch of the starting system has sintered with the contact. If such problems do occur, replace the relay device of the starting system or replace the solenoid switch.

Through the above analysis, it can be seen that the occurrence of circuit failure of the starting system may be caused by a variety of reasons. When there is a fault, it is necessary to remove the factors that may lead to the fault, so as to determine the cause of the fault as soon as possible, then troubleshoot it.

Above all. It is of great significance to understand the common circuit failure, when the starting system has malfunctioned, we are easily to locate the failure point as soon as possible and take corresponding troubleshooting measures, to avoid the circuit failure and wear and tear in engine, the starting system will be restored in a short time.

4. When turn on the ignition switch, the starter motor doesn’t run

Symptom: turn the ignition switch to the 'on' position, the starter does not run.

The causes of failure

A. Battery itself is severe deficient. The joint of anode and cathode of battery is loose or other grease stains cause bad contact or the battery internal damage.

B. There is a fault in the ignition switch itself or in the starter relay.

C. The two contacts of the starter solenoid switch are severely ablated, resulting in poor contact between them, or the contact plate cannot connect the two contacts due to improper adjustment. 

D. The conduction of electricity between the commutator and brush is not smooth due to the ablative damage of the commutator.

E. Excessive wear of brush carbon rod causes excessive reduction of brush spring pressure, which leads to poor conductivity of brush and commutator. The brush is stuck in the brush frame and cannot contact the commutator, and the circuit of the brush is connected is faulty.

F. The motor excitation winding or armature winding has ground, short circuit or open circuit fault.

G. The armature core cannot be rotated normally due to excessive wear on the armature bush.

H. Circuit fault, short circuit, bad contact or error connection.

Fault diagnosis and troubleshooting

A. Check whether the storage power of the battery is sufficient and whether there is no fault in the power circuit. Turn on the headlight or honk the horn to check whether there is a fault in the power circuit.

B. Check whether the fuse wire of the starting system is burnt. If burnt, the fuse wire should be replaced.

C. Determine whether the fault is in the starter or control circuit. Turn the ignition switch to the starting position, and a test lamp (or a multimeter) can be used to check whether the terminal voltage of the starter is normal. If it is normal, it indicates the starter has an open circuit, short circuit or ground, and the starter needs to be removed for further maintenance. If it is abnormal, there is a fault in the circuit between terminal and the positive pole of the battery.

D. Check whether the starter relay "starter" terminal voltage is normal. If normal, it means the lead between the starter relay and the starter motor is broken. If abnormal, continue the following inspection.

E. Check whether the starter relay "ignition switch" terminal voltage is normal. If normal, check the starter relay and its power lines and lapped wires. If the voltage at the starter relay "ignition switch" terminal is detected to be abnormal, continue the following inspection.

F. Check whether the "starter" terminal voltage of the ignition switch is normal. If normal, it means the lead between the ignition switch and the starter relay is short circuit. If abnormal, continue the following inspection.

G. Check whether the "power" terminal voltage of the ignition switch is normal. If normal, the ignition switch is damaged. If it is abnormal, the circuit between the ignition switch and the positive electrode of the battery is short circuit and should be repaired.

5. Troubleshoot starter idle

Symptom: turn on the starter switch, the starter idles, unable to drive the engine.

The causes of failure

A. One-way clutch fails and slips. 

B. The starter was started too early. 

C. The drive gear or flywheel gear ring of the starter is damaged. 

D. The travel of the solenoid switch is too short. The drive pinion cannot engage with the flywheel gear ring.

Troubleshooting

Turn on the starter switch, then check the idling starter. There are two situations:

The first one is caused by the malfunction of control mechanism of the starter, that is, the drive gear of the starter does not engage with the flywheel gear(pinion).

The second is the gear ring of the flywheel gear has engaged with the drive gear of the starter, and the starter idles because of the slip of the one-way clutch.

Diagnostic methods

A. There is no clattering sound, one-way clutch sliding, need to replace the one-way clutch. If there is a clattering sound, it means the timing of the starter is too early or the starter's drive gear (or flywheel ring) is damaged. 

B. Check whether the drive gear or flywheel gear ring is damaged. If damaged, it needs to be replaced.

C. Adjust the timing of starter motor.

6. The starter sends out clicking noise

Symptom: when the ignition switch is turned on, the starter's moving iron core creates a continuous reciprocating motion sending out clicking noise.

The causes of failure

A. Damage to gear ring of starter or flywheel.

B. The solenoid switch keeps the coil in sort circuit or poor lapping. Improper travel adjustment of the solenoid switch, it causes the starter drive gear not to gnaw into the fly gear ring before the main circuit of the starter is switched on prematurely.

C. Starter relay contact is disconnected or the voltage is too high.

D. Loose starter mounting screws or clutch housing.

Fault diagnosis and troubleshooting

Check whether the starter's set screws are loose or the clutch housing is loose, and whether the meshing gear pair is overworn. If all are normal, the battery voltage can be tested with a multimeter. When starting the engine, the battery voltage shall not be lower than 9.6V. If the voltage value is too low, it indicates the battery internal damage or power deficit is serious, it should be replaced. If the normal voltage value, indicates the battery performance is in good condition, when switching on the starter switch, there is clicking noise, indicates the holding coil of solenoid switch is not properly grounding and the short circuit, or the disconnection voltage of the starter relay is too high. If the solenoid switch and the starter relay are repaired or replaced respectively, the fault can be eliminated.

Conclusion 

The failure points of the automobile starting system include: the starter switch has a bad contact. Excessive wear of the motor brush leads to a poor contact with the commutator. Insufficient spring elasticity. Electric brush gets stuck. Contact plate is ablative, dirty, warping or uneven. Starter relay contact ablation. Starter relay coil is short circuit, open circuit or poor grounding. One-way clutch failure. Armature coil is short circuit or open circuit. The commutator is dirty, open circuit or short circuit. Battery anode and cathode column damage, connector loose or oxidation.