Fault of Ignition Switch

Working Principle

Turn on the ignition switch and the engine starts to run. The disconnector cam rotates continuously to make the disconnector contacts open and close continuously. When the contact of the disconnector is closed, the current of the battery starts from the positive terminal of the battery and flows back to the negative terminal of the battery through the ignition switch, the primary winding of the ignition coil, the movable contact arm of the disconnector, the contact, the distributor case overlap.

When the contact of the disconnector is opened by the cam, the primary circuit is cut off and the current in the primary winding of the ignition coil drops rapidly to zero, and the magnetic field around the coil and in the iron core also decays rapidly and disappears, so that an induced voltage is generated in the secondary winding of the ignition coil, which is called the secondary voltage. The current passing through it is called the secondary current, and the circuit through which the secondary current flows is called the secondary circuit. After touching off, the higher the rate of primary current drop, the greater the rate of change of flux in the core, and the higher the induced voltage generated in the secondary winding, and the more likely to break through the spark plug gap. When the ignition coil flux change in the core, not only in the secondary winding to produce high-voltage electricity (mutual inductance voltage), but also in the primary winding to produce self-induced voltage and current. In the contact separation, the primary current down moment, the direction of the self-induced current and the direction of the original primary current, its voltage up to 300 V. It will penetrate the contact gap, between the contacts to produce a strong electric spark, which does not only makes the contacts quickly oxidation, ablation, affecting the normal work of the disconnector, while the rate of change of the primary current decreases, the voltage induced in the secondary winding is reduced, the spark in the spark plug gap becomes weaker, so that it is difficult to ignite the mixture. so that it is difficult to ignite the mixture.

In order to eliminate the adverse effects of self-induced voltage and current, there is a capacitor C1 connected in parallel between the contacts of the disconnector. at the moment of contact separation, the self-induced current charges the capacitor, which reduces the spark between the contacts, accelerates the decay of the primary current and flux and increases the secondary voltage.

No sound from the starter

The ignition switch is in the start position, but the starter does not make any sound.

When such a phenomenon occurs, the driver can use some information shown by the device to initially determine the general scope of the fault. Possible causes are: the battery is dead, the starter itself is damaged, the wiring is somewhere in bad contact or a broken circuit.

To determine whether the battery has power, you can press the horn switch on the steering wheel to listen to the sound of the horn, or turn on the headlights to check the brightness of the headlights to determine. If the horn does not sound and the lights do not light up, find the location of the battery, check whether the positive and negative battery pole clamps are loose and if they can be tightened (Note: when tightening the positive pole, operate carefully to prevent it from short-circuiting with the negative pole and the frame). If the battery itself is dead, divided into battery self-discharge and power equipment abnormal power consumption, or line short circuit in three cases, you need to ask professionals to identify it.

If the battery power is sufficient, is the starter itself or starter line failure caused by the starter does not have any sound, the driver himself is difficult to exclude, can first check with the starter-related line plug whether there is an off, false connection, and then can do is to use a wooden stick type of handy tools to knock the starter, activities and starter-related wiring harness, so that poor contact can be in the process of vibration, kneading the solenoid valve coil temporarily Restore normal function, while doing so while starting the equipment, may be able to start the equipment. After driving back to the site, send the equipment to be repaired in time to avoid the recurrence of the same failure.

If you encounter damage to the ignition switch, then it should be promptly replaced with a new ignition switch, the cost of the ignition switch is actually within acceptable limits.

Safety Hazards

The ignition switch may be damaged by an overweight or shaking key ring. If the keyring is hit, or if the car is driven on an uneven surface, the switch may suddenly shift from "Drive" to "Self Check" (also called "A C C") or "Off". With the ignition switch in the latter two positions, power to the steering and braking systems will be cut off, which could result in a loss of control of the equipment and cause a crash. In the event of a crash, the airbag will also fail to open due to the power cut, making it difficult to protect the driver. General Equipment reminds users that defective equipment, even if the ignition switch is replaced, it is best not to hang heavy objects on the car keys.