The correct use of automotive instrumentation

Commonly used automotive electrical instruments mainly include ammeters, fuel gauges, water temperature gauges, and oil pressure gauges. Its role is to identify and indicate the performance and status of all relevant parts, providing the basis and guidelines for proper use and maintenance of the engine. In order to ensure that each instrument can work properly and accurately indicate the performance and status of each relevant part, it must be properly used and maintained in time.

1, often wipe the surface of the instrument, on the one hand to prevent dust and oil intrusion inside the instrument damage the watch, on the other hand is also easy to observe the dynamics of the instrument pointer.

2. Grasping the performance of each instrument and the relationship between the status of the indicator and the relevant working condition of the engine, so as to judge the working condition of the engine and find the fault location and cause according to the status of the indicator.

3. When starting the engine, it is necessary to observe the dynamics of each instrument, find abnormalities, and deal with them in a timely manner. During the operation of the engine and the running of the vehicle, the dynamics of each instrument should also be observed frequently in order to grasp the working conditions of each related system.

4. Instruments with different voltage values ​​shall not be used in addition to the ammeter to avoid damage to the instrument.

5. The sensor performance of electrothermal and electromagnetic instruments is quite different. For example, for a variable resistance sensor with an electric fuel meter, the resistance value decreases with the oil level of the tank, while the resistance value of the variable resistance sensor with an electromagnetic fuel meter has the opposite effect. The sensor of the electric oil pressure gauge The variable resistance value decreases with increasing oil pressure, and the change in the variable resistance value of the electromagnetic oil pressure gauge is just the opposite; the thermistor of the electrothermal water temperature sensor has a resistance value of 220 ohms at a water temperature of 50°C. When the water temperature is 115°C, the temperature is reduced to 20 ohms, and the thermistor of the electromagnetic water temperature sensor has a high resistance value when the water temperature is l00°C, and the resistance value of the thermistor of the electromagnetic water temperature sensor is significantly reduced when the temperature continues to increase. Therefore, electrothermal and electromagnetic instruments and their sensors should be used together and must not be used interchangeably or replaced individually.

6, the water temperature sensor must be well grounded, the sensor's conductor shall not be iron, short circuit, so as not to damage the water temperature meter.

7. When installing the oil pressure sensor, make the “↑” mark upward, otherwise it will reduce the accuracy of the oil pressure gauge indication.

8, the electromagnetic terminal of the fuel meter should be connected to the sensor, the upper terminal then the ignition switch. Otherwise, the pointer always points to "0".

9. The movement of the float in the fuel tank should be flexible; the fuel tank and fuel gauge sensor grounding should be reliable. If the ground is bad, the pointer will always point to the "0" side.

10. When testing the fuel gauge system with electricity, the sensor shall not be taken out of the fuel tank to prevent the fuel tank from catching fire due to the sliding of the variable resistance of the sensor.

11. When the regulator circuit is equipped with a voltage regulator, its housing should be reliably grounded. When the regulator is damaged, the instrument cannot be directly connected to the power supply to avoid damage to the instrument.

12. The positive and negative polarities of the ammeter cannot be reversed. If the car is a negative ground, the ammeter "-" connection column should be connected to the battery fire wire (positive), "+" connection column to the alternator fire wire.

13. Before the wiring of the ammeter, the contact surfaces of the washers, nuts and bolts should be polished with sandpaper. When installing the nuts, it is better to apply a little clean oil, which can prevent corrosion and facilitate disassembly; flat insulation washers should be intact, and the insulating gaskets should be A flat washer should be installed between the spring washers and firmly connected to prevent the wire from heating due to poor contact, and even burn out the instrument and wiring harness.

14, regular inspection of electrical instrumentation. When there is no detection instrument, it can be compared with the standard instrument: the indication error of the current meter should be less than ±20%; the indication error of the oil pressure gauge should be less than ±10% when the oil pressure is 0.2 MPa, and the oil pressure is 0.5 MPa. Should be less than ±20%.