Car body electrical practice

LESSON 2 MAINTENANCE AND REPAIR OF LIGHTING SYSTEM

I. IMPLEMENTATION GOAL

After completing this lesson, students will be able to:

- Identify types of lighting on cars

- Can connect lighting system circuit

- Correctly describe the symptoms of damage and the causes.

- Disassemble, install, check, maintain and repair lighting systems to ensure technical requirements.

- Ensure safety in work and industrial hygiene

II. LESSON CONTENT

1. General description

Figure 2.1. Types of lights on cars

1,3. Right front light cluster; 2. Engine compartment relay box; 4. Reverse light switch; 5,7. Front fog light cluster; 6. Neutral parking position switch; 8,18. Side turn signal lamp; 9,17. Turn signal lamp on rearview mirror; 10,14,15. Right front door light switch; 11. Map light; 12. Ceiling light; 13. Luggage compartment light; 19,21. License plate light cluster; 20. Brake light on glass; 22,24. Rear light cluster; 23. Luggage compartment door switch; 25. Brake light switch; 26. Combination switch cluster; 27. Hazard switch

The car lighting system has functions such as:

- Lighting to ensure safety while traveling on the road:

Lighting includes headlights (used for long distance lighting) and low beams (used for short distance lighting). In addition, cars are also equipped with fog lights (fox lamps) when encountering foggy weather. Fog lights are also known as fog lamps.

- Use lights to signal such as taillights, turn signals, brakes, stops and parking...

- Lighting in the vehicle and luggage compartment or trunk. For the lighting system when entering the vehicle, it provides convenience when entering or exiting the vehicle at night.

A light control circuit usually includes: battery, fuse, wire, light bulbs (also known as electrical load) and control switch. On a car, under the steering wheel, there is a switch cluster that can control many loads such as: lights, horn, wipers, turn signals... This switch cluster is also called a combination switch cluster.

Car lights are usually arranged as shown in Figure 2.1.

The light control switch cluster is located on the left side of the combination switch cluster. This light control switch cluster can control lights such as taillights, size lights, high-low beams, and turn signals. How to use the switch is described as in Figure 2.2

Picture

Function

Figure 2.2. Car light control switch

OFF

All the lights are off.

Parking lights, tail lights, license plate lights, overhead lights

The dashboard is bright

Headlights and all lights

All of the above are bright.

Auto

Automatic headlight mode

motion activated

Maybe you are interested!

On vehicles manufactured in recent years, the headlights can turn on automatically when moving in low light environments, the light intensity of the headlights can be changed, and the light beam of the headlights can also be changed automatically when the vehicle turns. If the lighting system is controlled by the lighting control ECU, the operation and control are described as follows

- When any of the following conditions are met, the ceiling light will gradually brighten.

+ There is any door open.

+ Any door is unlocked when the ignition is OFF and all doors are closed.

+ The electric lock is turned from ON to OFF when all doors are closed.

- When one of the following conditions is met, the ceiling light will turn off.

+ The electric lock is turned from OFF to ON when all doors are closed.

+ All doors are locked when the power switch is OFF.

- Lights up for about 15 seconds, and then fades out when all doors are closed with the power off.

- When all of the following conditions are met, the lamp control ECU will turn off all lamps.

+ The key is not in the ignition lock.

+ No change in door lock status for 20 minutes.

- When any of the following conditions are met, the battery save counter will be cleared.

+The key is in the ignition lock.

+ Any door open.

2. Maintenance and repair

2.1. Dimensions of lights and high-beam and low-beam lights

The front lighting system is the most basic and important lighting system on the vehicle to ensure working conditions for the driver, especially at night. Front lighting is always improved to increase vehicle safety when traveling on the road.

Headlights today are manufactured based on two levels of light: high beam and low beam. The headlight's ability can be from 180 - 250m and the near beam from 50 - 75m . Headlights are one of the devices that consume a lot of power on cars, in high beam mode it is 45 - 70W , in near beam mode it is 35 - 40W .

Headlights play an extremely important role when a car is moving, so headlights are always improved to improve lighting and save energy... Headlights often use the following types of bulbs:

- Incandescent bulbs, halogen bulbs

- Xenon lights: Low beams use Xenon lights, high beams still use Halogen bulbs

- Xenon Bi-xenon Headlights: Both high and low beams use Xenon. The above two types of lights are also known as HID lights.

- Led lights: This type of light has high light intensity but low power and is used in most modern cars today.

The dimmer and high beam are always connected to the same circuit, the dimmer is installed behind the white bulb, the red lens depending on the type. The high beam includes the high beam and the low beam. There are many methods of connecting the circuit but all must satisfy the following requirements:

- Do not turn on the ignition, turn on the light selector switch at the Tail position, only the size light is on.

High beam and low beam do not light up

- Do not turn on the ignition, when turning the light selector switch to the Head position, the size light will still be on and the high beam or low beam will be on. At this time, to change the phase or low beam, select the Phase or Low position on the Phase-Low beam switch.

- The ignition is not turned on, the light selector switch is in the OFF position, the size light, high beam and low beam do not light up, turn on the flashing switch, the headlights light up

When wiring a circuit diagram, it is very important to find out the meaning of the terminals in the combination switch assembly (if there is no EWD). The search sequence is performed in the following order. The instrument used is an ohmmeter based on the principle of exclusion.

- Control for all switches to OFF mode

- Find the left and right turn signal control poles

- Find the phase flash control pole

- Find the size lamp control terminal at the lamp selector switch

- Find the high-low beam control terminal on the light selector switch

- Find the control pole in phase or core mode

2.1.1. Circuit diagram

a, Type without relay

Figure 2.4 High-beam-low-beam system without control relay

1. Battery; 2. Fuse; 3. Headlight;

4. Headlight; 5. Combination switch cluster

b.Type using positive standby relay

Figure 2.5 Diagram of the standby high-beam-low beam control switch

1. Battery; 2. Main fuse; 3. Dimension lamp relay;

4. High beam-low beam relay; 5. High beam fuse; 6. Low beam fuse;

7. Dimension lamp fuse; 8. Low beam headlight cluster; 9. High beam indicator light; 10. Dimension lamp; 11,12. Combination switch cluster

c. Type using standby negative relay

Figure 2.6 Circuit diagram of standby negative light control

1. Battery; 2. Vehicle size light relay; 3. Headlight relay;

4. High-beam-low-beam relay; 5. Low-beam headlight assembly; 6. High-beam indicator light;

7. High-beam/low-beam selector switch; 8. High-beam/low-beam selector switch

d, Automatic headlight circuit

Figure 2.7 Automatic headlight circuit diagram

1. Battery; 2, 3,12. Fuse; 4. Electric lock; 5. Combination switch;

6. Auto headlight sensor; 7. Headlight; 8. ETACSCM;

9. Dimension lamp; 10. Headlight relay; 11. Dimension lamp relay

In this circuit, sensor number 6 detects the light conditions in the area where the vehicle is moving. For example, when entering a dark tunnel, the sensor will automatically connect negative to relay number 11 so that the headlights are turned on.

e, Automatic Headlight Switching Circuit (AFS)

Figure 2.8 Block diagram of lighting system with headlight rotation function

Figure 2.9 Schematic diagram of the AHLS automatic headlight control system circuit

1. Battery; 2, 5. Fuse; 3. Alternator; 4. Ignition switch; 6. Turbocharger; 7. HID lamp;

8. Diagnostic connector; 9. AHLS CM; 10. Wheel speed sensor;

11. ECU; 12. Headlight relay; 13. Light control switch

When the vehicle moves into a turn, there will be dark areas where the light cannot shine, this system has the function of controlling the headlight beam into the dark area to ensure traffic safety when turning. This light will turn on when receiving signals: turn signal, vehicle speed, steering angle

Figure 2.10 Light area of a vehicle equipped with a headlight rotation function

1. Conventional lighting system

2. Lighting system equipped with headlight rotation function

In addition to the headlight rotation function, the system is also equipped with a headlight direction control function when the truck body is unevenly distributed on the vehicle, such as when the vehicle is carrying more people or luggage or entering roads with large bumps.

Now the height sensor works and will adjust the light direction.

Figure 2.11. Schematic diagram of the smart headlight system

1. Headlight; 2. Control switch; 3. AFS indicator light

Figure 2.12. Structure of a smart headlight cluster

1. Headlight; 2. Headlight rotating stepper motor (headlight actuator)

2.1.2. Symptoms and suspected areas

The faults in the lighting system of the vehicle may be similar, but the suspected problem area is different because it depends on the structure of the circuit and its circuit diagram. If a circuit has many components, the suspected problem area will be larger. Therefore, this symptom chart is only for Toyota vehicles with the connection diagram in Figure 2.10. For each lighting system, a circuit diagram is required to localize the fault area of the system.

Symptom

Suspicious area

All headlights are not on.

- Light control switch

- Power cord or connector

Only one headlight (low beam) is on.

- Light bulb

- Fuse

- Power cord or connector

The low beam headlights do not illuminate.

- Light control switch

- Power cord or connector