Headlights are blinking while the engine is running, what to do

If the headlights are blinking when the engine is running, you need to find out the cause of the problem and eliminate it. It does not just occur and most often signals a malfunction in the electrical equipment or other malfunctions. If you do not pay attention to the blinking of lights, it can lead to various troubles - from the failure of the lamps at the most inopportune moment to the breakdown of the generator, because of which it will be impossible to continue driving.

Causes of headlights blinking when the engine is running

The system of voltage supply to the headlights is standard on all cars. The current is supplied through a wire, and the minus is connected to the car body. When the engine is running, the alternator is responsible for the electrical supply. In this case, the problem is almost always observed when the engine is running at idle speed, when the voltage in the on-board network is minimal.

Voltage is higher than normal

A working alternator should give out 14 to 15 volts, this is the normal range, providing power to all the equipment in the car. If the value is higher, it leads to overloads and systems malfunction, which causes the lights to start blinking. But this is not the most dangerous thing, the overloads can cause expensive electronics to fail, resulting in much higher repair costs.

Such a malfunction most often results in replacing the alternator. Or it is necessary to give it for diagnostics to identify problems and fix them. Driving in this case is undesirable, so as not to overload the electrical equipment.

The voltage should not exceed 15V.

Voltage below normal

This variant is much more common, since during operation, the generator and other elements wear out. Over time, this leads to a drop in voltage, most often the problem is as follows:

1. Wear of the diode bridge or other elements of the generator. In this case, the equipment is either repaired or replaced. Often the operation of this unit is disturbed by worn bearings, which do not allow normal rotation of the shaft.
2. The alternator drive belt tension is loose. The belt must be well tensioned for the motor to transmit the force for current generation. If it is loose, the current output will deteriorate.
3. Severe wear and tear on the battery means that it can no longer hold voltage. And the alternator is not able to supply all the current consumers at idle speed, which is why the headlights flicker.
4. High load on the generator. This can be when using powerful audio systems and other elements that consume a lot of energy. In this case, simply turn down the sound or turn off what overloads the network.

Sometimes the problem occurs due to the fact that when replacing the alternator a version with less power was supplied and it is simply not enough for normal operation.

Other causes

Headlights can also flash due to malfunctions in other systems. The most common variants are as follows:

1. Damaged or poor contact of the ground wire going from the headlight to the car body.
2. Problems with the power supply in LED bulbs. This is especially common in cheap products. After a short time, the elements begin to work intermittently and the problem can only be solved by replacing them.
3. The wear and tear of xenon bulbs. This light source has a certain lifespan and when the replacement time approaches, the bulbs may blink. Also with xenon it can indicate malfunctions or interruptions in the ignition unit.

If one bulb began to shine yellow, it means its life is coming to an end.

Video: Looking for the cause when flickering headlights and all the light in the cabin.

Troubleshooting rules

To quickly identify the cause of flickering light, you need to follow a simple instruction. For work, you will need a multimeter or voltmeter, without it you will not be able to check the indicators. The process consists of the following steps:

1. Check the voltage produced by the alternator. If it does not correspond to the norm, you need to remove the unit and take it to the diagnostics or go to the car service, so that all the necessary work was done there.
2. With the engine turned off you should check the tension of the belt going to the generator. When you press it firmly with your thumb, it should flex slightly. If the tension is weak, it is necessary to tighten the belt.
3. The voltage of the battery is measured. When the charge is low, the battery should be recharged. If the battery is not taking a charge, the electrolyte level should be checked and its density should be measured (on serviced models). Non-maintained ones are simply replaced.
4. Measure not only the output voltage on the alternator, but also the current coming directly to the headlight socket. If the difference is large, it means if there is a problem with the wiring or contacts, they should be fixed.
5. The ground wire from the headlight to the body is checked. It should be tested, and the point of contact should be cleaned and well clamped using a washer.
   The ground wire contact often deteriorates due to corrosion.
6. If only one bulb is blinking, the easiest way to check it is to simply swap light sources. If the flicker is on the same light source, then it's a problem. This is true for xenon and LED equipment.

If the lamp fault indicator lights up on the dashboard, it means that the lamp is not working properly.

What mistakes are made when repairing headlights

If you carry out the repair incorrectly, the problem may return. Therefore, it is worth remembering simple tips that will help avoid mistakes:

1. Only pairs of bulbs should be changed.. If even a problem with one, you can not put even the same one, as the life of the light sources are different and eventually the work of the system will be broken.
2. Strip the contacts if there is a loss of voltage. This measure is temporary and the fault will soon return. It is much better to put an additional relay, coming from the battery, through which the headlights are powered. Then there will never be any voltage sags.
3. You shouldn't buy cheap bulbs.Especially it concerns LEDs and xenon bulbs. Their life is much less than the declared.

Video Block: Blinking light at idle.

To get rid of the flickering light is not difficult, because finding the problem does not take much time and does not require sophisticated equipment. More often than not, you can fix the problem on your own, the main thing is to find out the cause of the flicker correctly.