What Is a Dashpot?

The car dashboard is a device that reflects the working conditions of various systems of the vehicle. Common indicators are the fuel indicator, cleaning fluid indicator, electronic throttle indicator, front and rear fog lights, and alarm lights.

Car dashboard

The car dashboard is a device that reflects the working conditions of various systems of the vehicle. Common fuel

The speedometer is actually composed of two meters. One is a speedometer and the other is an odometer.

Traditional speedometers are mechanical. A typical mechanical odometer is connected to a flexible shaft. There is a steel cable inside the flexible shaft. The other end of the flexible shaft is connected to a gear of the transmission. Gear rotation drives the wire rope to rotate. The wire rope drives a magnet inside the odometer cover to rotate. The shroud is connected to the pointer and the pointer is set to the zero position by a hairspring. The speed of the magnet's rotation causes changes in the size of the magnetic field lines. The balance is broken and the pointer is thus driven. This speedometer is simple and practical. Is widely used in large

The tachometer is usually set in the dashboard. Placed symmetrically with the speedometer. The tachometer works according to the magnetic principle. It receives a pulse signal generated when the primary current in the ignition coil is interrupted. This signal is converted into a displayable speed value. The faster the engine speed, the more pulses generated by the ignition coil, the greater the speed value displayed on the table.

Cars are generally electronic tachometers, with pointer and LCD digital display. There are digital integrated circuits in the table. It calculates the voltage pulse sent from the ignition coil and then drives the pointer to move or display it digitally. Another type of tachometer is to display the tachometer value after taking out the pulse signal from the generator and sending it to the tachometer circuit for interpretation. However, it is affected by factors such as slipping of the generator belt. The values are less precise.

1 Timing toothed belt indicator

Certain imported cars that use a timing toothed belt drive and an overhead camshaft generally limit the life of the engine timing toothed belt (about 100,000 km) and must be replaced at that time. In order to enable the maintenance personnel to replace the timing toothed belt on time, a timing belt life indicator "T.BELT" is set on the instrument panel, and the following points need to be noted during use.

(1) When the indicator light is on, observe the odometer immediately. If the cumulative mileage reaches or exceeds 100,000 km, the timing toothed belt must be replaced, otherwise the timing toothed belt may break and the engine will not work properly.

(2) After replacing the new timing toothed belt, turn off the rubber stopper on the outside of the reset switch on the odometer dial, and press the reset switch inside with a small round bar to make the timing toothed belt indicator go out. If the indicator does not go out after operating the reset switch, the reset switch may fail or the line may be grounded, and the fault should be repaired and eliminated.

(3) After replacing the new timing toothed belt, remove the odometer and adjust all readings on the odometer to the "0" position.

(4) If the car has not been running for 100,000 km, the indicator light is on, you can press the reset switch to turn off the timing belt indicator light.

(5) If the timing toothed belt is replaced before the indicator light comes on, remove the odometer and reset the interval counter so that the interval meter in the odometer

The zero position of the counter gear is aligned with its drive gear.

(6) If only the odometer is replaced without the timing toothed belt, the counter gear should be set to the position of the original odometer.

2 Exhaust temperature warning light

Due to the installation of a three-way catalytic converter on the exhaust pipe of modern cars, the exhaust temperature has increased, but the excessively high exhaust temperature is likely to cause damage to the three-way catalytic converter, so this type of car is also equipped with an exhaust temperature Alarm device. When the exhaust temperature warning light is on, the driver should immediately reduce the speed or stop the vehicle. When the exhaust temperature drops, the warning light will go out automatically (but after the fusible exhaust temperature warning light is on, if it is not adjusted or repaired , Will stay on), if the exhaust temperature warning light does not go out, you should find out the reason, and continue driving after troubleshooting.

3 Brake warning light

The brake warning light is red with a "!" Symbol inside the circle. If the red brake warning light is on, the following conditions exist in the braking system:

(1) The friction plate of the brake is severely worn;

(2) The brake fluid level is too low;

(3) The parking brake has been applied (the parking brake switch is closed);

(4) Under normal circumstances, if the red brake warning light is on, the ABS warning light will be on at the same time, because ABS cannot play its due role when the conventional braking system is faulty.

4 Brake anti-lock warning light

</ strong> The brake anti-lock warning light is yellow (or amber) and the pattern is "ABS" in the circle.

For cars equipped with anti-lock braking system (ABS), when the ignition switch is turned to the "ON" position, the ABS warning light on the instrument panel lights up for 3 s 6 s. This is a self-test process of ABS, which is normal. . Once the self-test process is over, the alarm light will go out if the ABS is normal. If the ABS warning light continues to light after the self-test, it means that the ABS electronic control unit detected a failure that is not conducive to the normal operation of the anti-lock braking system (for example, when the vehicle speed exceeds 20 km / h, the wheel speed sensor signal is abnormal) Or EBV (Electronic Brake Force Distribution System) has been turned off. In this case, if you continue to drive, because the function of the braking system has been affected, the electronic braking force distribution system no longer adjusts the braking force of the rear wheels. When braking, the rear wheels may lock up in advance or a tail flick occurs. The danger of an accident should be repaired.

When the vehicle is running, the ABS warning light flashes or stays on to indicate that the degree of failure is different. The blinking indicates that the failure has been confirmed and stored by the ECU; the steady light indicates that the ABS function is lost. If you find that the car's braking performance is abnormal during driving, but the ABS warning light does not light, it means that the fault is on the mechanical part and hydraulic parts of the braking system, not on the electronic control system.

5 Drive anti-slip control indicator

The pattern of the drive anti-slip control system (ASR) indicator is a "" symbol inside the circle.

For example, FAW Bora 1.8T sedan has the function of anti-skid control. When the car accelerates, if ASR detects the tendency of the wheel to slip, it will reduce the engine's output torque by intermittently turning off the fuel injection and delaying the ignition advance angle to adjust. Traction to prevent the drive wheels from slipping.

ASR works with ABS in any speed range. When the ignition is turned on, ASR is automatically enabled, which is the so-called "default selection". The driver can manually cancel the anti-skid control by the ASR button on the dashboard. When the ASR indicator on the dashboard lights up, it means that ASR has been turned off.

Under the following conditions, a certain degree of wheel slip is required, and the ASR system should be turned off.

(1) Wheels are fitted with snow chains.

(2) The car is driving on snow or soft roads.

(3) The car is stuck somewhere and needs to move back and forth to get out of the predicament.

(4) When the car starts on a ramp, but the adhesion of the wheels on one side is extremely low (for example, the right tire is on the ice and the left tire is on a dry road).

If this does not happen, do not turn off ASR. Once the ASR indicator lights up while the car is running, it means that the electronic control unit (ECU) has turned off the drive anti-skid system, and the driver will feel that the steering wheel is operating heavily. According to the working principle of the ABS / ASR system, when the system fails, the transmission of the wheel speed sensor signal will be interrupted, and other control systems (such as steering assistance systems) that require wheel speed signals to work normally will be affected at the same time. Only after the fault of ASR is eliminated, the phenomenon of heavy steering operation will disappear.

6 Airbag indicator

The airbag system (SRS) indicator has three display methods, one is "SRS", the other is "AIR BAG" (Toyota cars produced before August 1992), and the third is "airbag protection occupant" graphics.

The main function of the SRS indicator light is to indicate whether the airbag system is in a normal state, and it has a self-diagnostic function of the fault. If the SRS indicator is always on after the ignition switch is turned to the ON (or ACC) position, and the fault code is displayed again, it indicates that the voltage of the battery (or the backup power of the SRS electronic control unit) is too low, but the SRS electronic control unit is designed When this fault is not coded into the memory, there is no fault code displayed. When the power supply voltage returns to normal for about 10s, the SRS indicator will automatically turn off.

Because SRS is not used normally, it will be discarded once it is used. Therefore, this system does not show the failure phenomenon during use like other systems in the car. It must rely on the self-diagnostic function to find the cause of the failure. Therefore, the SRS indicator and fault The code becomes the most important source of fault information and diagnostic basis.

7 Danger warning lights

Hazard warning lights are used to warn other vehicles and pedestrians in the event of a major breakdown or emergency. The hazard warning signal is indicated by the front, rear, left and right turn signals flashing simultaneously.

The hazard warning light is controlled by an independent switch, and generally shares a flasher with the turn signal light. When the hazard warning light switch is turned on, the turn signal circuits on both sides are turned on at the same time, and the front, rear, left, and right turn signals and the turn indicators on the instrument panel flash at the same time. Because the hazard warning light circuit connects the flasher to the battery, the hazard warning light can also be used when the ignition is turned off and the vehicle is stopped.

8 Battery indicator

Indicator for battery working status. Lights up when the electric switch is turned on, and goes out when the engine starts. If it does not light or stay on, check the generator and circuit immediately.

9 Fuel indicator

The indicator light indicating insufficient fuel. When the light is on, it means that the fuel is about to run out. Generally, the vehicle can still run for about 50 kilometers from the time the light is on until the fuel is exhausted.

10 Cleaning liquid indicator

</ strong> Indicator showing the amount of windshield washer fluid. If the washer fluid is about to run out, the light is on, prompting the owner to add the washer fluid in time. After adding cleaning fluid, the light goes out.

11 Electronic throttle indicator

This lamp is more common in Volkswagen's models. When the vehicle starts the self-test, the EPC lamp will light for a few seconds, then go out, and a failure will occur. The lamp will light up and should be repaired in time.

12 Front and rear fog light indicators

This indicator is used to display the working status of the front and rear fog lights. When the front and rear fog lights are turned on, the two lights are on. The left side of the figure is the front fog light display and the right is the rear fog light display.

13 Turn indicator

When the turn signal lights, the corresponding turn signal flashes at a certain frequency. When the double flashing warning light button is pressed, both lights are on at the same time, and the indicator light goes off automatically after the turn-off light goes out.

14 High beam indicator

Shows whether the headlight is in the high beam state. Normally, this indicator is off. Lights up when the high beam on the dashboard is turned on and the momentary high beam function is used.

15 Seat belt indicator

The indicator light that shows the status of the seat belt. Depending on the model, the light will light up for a few seconds to prompt, or it will not go out until the seat belt is fastened, and some cars will also have a sound prompt.

16 O / D indicator

The O / D gear indicator is used to display the working status of the automatic gear O / D gear (Over-Drive). When the O / D gear indicator flashes, it means that the O / D gear is locked.

17 inner loop indicator

This indicator is used to show the working status of the vehicle air conditioning system, which is normally off. When the inner cycle button is turned on and the vehicle turns off the outer cycle, this indicator lights automatically.

18 Width Indicator

The width indicator light is used to display the working status of the vehicle's width indicator light, which is normally off. When the width indicator light is on, the indicator light will be on.

19 VSC indicator

This indicator is used to show the working status of the vehicle's VSC (Electronic Body Stabilization System), which mostly appears on Japanese cars. When this indicator is on, the VSC system has been turned off.

20 TCS indicator

This indicator is used to show the working status of the vehicle's TCS (Traction Control System), which mostly appears on Japanese cars. When this indicator is on, the TCS system has been turned off.

The oil pressure sensor is a piezoresistive sensor. Threaded to the engine oil line. The pressure of the oil pushes the contact piece to move on the resistance, which changes the resistance value and affects the amount of current through the instrument to ground. Drive the pointer to swing. Because the oil pressure has a certain pressure range, for clarity. At present, the oil pressure gauge of many cars is indicated by an indicator light. If it is still on when the engine is running. It means that the engine lubrication system may be abnormal.

The water temperature sensor is a thermistor sensor. Screwed to the engine cooling water channel. The thermistor determines the amount of current flowing through the coil of the water temperature meter. Thereby, the hand of the meter head is driven to swing. In the past, the cooling water of automobile engines was used as the tap water. Many automotive engine cooling systems now use specialized coolants. It is also called a coolant temperature gauge.

There are two coils in the fuel gauge. On the "F" and "E" sides, the sensor is a variable resistor controlled by the height of the float. The change in resistance determines the strength of the magnetic field lines of the two coils. This determines the deflection direction of the pointer.

Water temperature and fuel gauges are also indicated by indicators. When the water temperature indicator is on, the water temperature is too high. The fuel indicator lights up to indicate that the fuel is approaching a low point as an auxiliary reminder.