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autometer fuel level gauge troubleshooting
Principle analysis of automobile fuel level gauge:
The display of the car's oil level is detected by an oil level sensor float (integrated on the oil pump) installed in the fuel tank. The oil level sensor is similar to a sliding resistor piece, and the float is connected to the sensor through a metal rod. When the float floats up and down, it changes the resistance value inside the sensor.
When we refuel, the float will rise with the increase of oil volume, and then the float will drive the sliding vane in the oil level sensor to move, which can output different resistance values under different liquid levels. This resistance value is transmitted to the combination instrument through the whole vehicle wiring harness. After the conversion and processing of the electrical signal, the pointer of the driving oil gauge points to the equivalent position
Reasons for inaccurate fuel gauge readings
The fuel gauge pointer reading is not accurate, and the fuel level sensor has a high probability of being damaged. Common reasons for the inaccurate reading of the fuel gauge are: 1. The fuel gauge or instrument is faulty. 2. The fuel sensor or circuit is faulty. We can short-circuit the harness connector of the fuel sensor and turn on the ignition switch. At this time, the position of the fuel gauge should be in the "F" or full position. If this position is not pointed to, the instrument panel is damaged. For the inspection of the fuel sensor, we measure the resistance value of the sensor. If the above inspection data are all good, then it is the wiring problem of the sensor.
Trouble shooting process
First check with the diagnostic computer, no fault codes are found. According to the customer's description, the fuel gauge of the car was high and low. Remove the fuel pump and measure the resistance value between the high and low positions of the float. It is between 50 and 289 ohms, which is normal. Continue to check the related lines of the oil level sensor. Because this line exists in the body wiring harness, you can only check the plug pins and the power supply grounding line first. According to the line inspection, there is no abnormality. In order to ensure that the plugs are in good contact, the plugs at both ends of the oil pump controller and the instrument have been processed. It is really difficult to judge the fault point. Generally, the fuel level is not accurate. We will measure the fuel level sensor. However, if the above reasons are excluded and the fault is not solved, then we need to study the working principle and structural characteristics of the fuel gauge. Analysis, you can find the fault and eliminate it.
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