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After the beginning of winter, many failures are caused by this sensor, which is the first urea level temperature sensor we talked about, which integratesUreaThe temperature and urea level sensor monitors the temperature of urea in the urea tank, integrates a cooling water heating pipe, which is used for heating and thawing the system in cold areas, and can heat the urea solution to prevent the system from failing to work normally due to crystallization of urea in cold weather. The urea level of the urea tank is detected, the urea float floats according to the urea level, and the percentage of urea is displayed on the instrument panel. Timely remind to add urea solution.

urea float

In terms of function, the liquid level sensor is divided into heating type and non-heating type. The main difference can be seen from the number of joints. The non-heating joint is generally 2 joints, and the heating type is generally 4-5 joints.

Liquid level sensor

From the point of view of installation, it can be divided into canned and non-canned.

Insert the urea pump into the urea tank and place the urea pump directly on the liquid level temperature sensor. The urea tube between the urea pump and the urea tube is omitted. This installation method is currently common on gas-driven urea pumps independently developed by Cummins and Sinotruk. The tank type is divided into heating and non-heating. Heated liquid level temperature sensor is shown in the following figure:

The non-heated liquid level temperature sensor is shown in the figure below:

Non-heated liquid level temperature sensor
Non-heated liquid level temperature sensor

The non-canned type is generally directly inserted into the urea tank, and then connected to the urea pump with the liquid inlet pipe and the liquid return pipe. At present, most vehicles on the market adopt this installation method.

Non-canned type is generally directly inserted into the urea tank

According to the volume of the urea tank, the height of the liquid level sensor is 16L, 35L, 45L, 80L, etc.

The liquid level temperature sensor is tightened or removed. Tighten the liquid level temperature sensor by turning it 30 degrees counterclockwise and loosen it by turning it 30 degrees clockwise.

Fault judgment method of liquid level temperature sensor

The easiest way to judge whether the liquid level temperature sensor is qualified under normal circumstances is to measure the resistance value of the liquid level temperature sensor. Each series of liquid level temperature sensors has a specific resistance value, but because there are too many types of liquid level temperature sensors in the world, it is more complicated for us to judge. The following are the resistance values of several common liquid level temperature sensors.

Measure the resistance value of the liquid level temperature sensor

For example:

Tomorrow Cummins CM2150

When the liquid level is 0%, the resistance is 18.64K?

When the liquid level is 100%, the resistance is 239?

Temperature: (room temperature 20°C)

Resistance: 3.84K?.

  CumminsCM2880

When the liquid level is 0%, the resistance is 16K?

When the liquid level is 100, the resistance is 1.14K?

Temperature: (room temperature 20°C)

Resistance: 3.8K?.

Weichai

When the liquid level is 0%, the resistance is 18.64K?

When the liquid level is 100%, the resistance is 239?

Temperature: (room temperature 20°C)

Resistance: 3.84K?.

For the circuit board instructions for the EDC17, the corresponding pins of the level temperature sensor:

Pin for level temperature sensor
Pin for level temperature sensor

There are 4 pins on the connector of the liquid level temperature sensor, 2 of the 4 pins are the bottom line, the power supply voltage of the 2 pins is 5V, the plug-in wire end is upward, and the connector of the liquid level sensor is facing itself; From left to right.

fault analysis

The sensor is damaged, the sensor connector is falsely connected, short circuit, and related wiring harness faults often cause the liquid level temperature sensor to report inaccurate liquid level display, abnormal temperature display, and the fault light is always on and the liquid level temperature sensor fault is reported. We look at the fault code:

Abnormal urea level and temperature display

Generally, the reading value of the liquid level temperature sensor is very important when repairing the car. Normally, the reading value of the temperature sensor is referenced according to the temperature of the car body and the ambient temperature. For example, our car is cold (the engine is not working) and the ambient temperature shows 5 ℃, but the reading value of the liquid level temperature sensor is -20 ℃, then the liquid level temperature sensor in this state must be problematic.

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