With the development of truck technology, the electronic degree of vehicles is becoming higher and higher. Even the accelerator we often say has become an electronic accelerator.
Today, let’s introduce a fault case that affects the normal operation of the vehicle due to the abnormal operation of the electronic accelerator caused by water ingress and corrosion of the vehicle harness connector.
Model: current situation
Engine model: quanchai 4b2-115c50
Emission standard: national five
Computer version model: edc17c81
Fault phenomenon: the engine fault light is on, and sometimes the refueling door does not respond.
Fault code: p213564 accelerator pedal 1 and accelerator pedal 2 signal rationality failure.
The fault code status is as follows:
According to the analysis of the fault phenomenon, the non response of the refueling valve is caused by the failure of the signal rationality of the fault code p213564 accelerator pedal 1 and accelerator pedal 2 of accelerator pedal signal.
1. Read the engine data flow, analyze the difference between the signal voltage of accelerator pedal 1 and accelerator pedal 2, and find that the signal voltage of accelerator pedal is normal, as shown in the following figure:
2. According to the above figure, the signal voltage of accelerator pedal 1 is 0.8V and the signal voltage of accelerator pedal is 0.4V. The multiple relationship between the two is normal, but the ECU reports a fault code and cannot be deleted of accelerator pedal signal.
3. Try to change the two signals synchronously through the pedal refueling door and keep a multiple relationship, but the fault code can’t be deleted. The failure code can’t be deleted means that the car can’t be handed over to the customer, so we decided to thoroughly investigate this fault point of accelerator pedal signal.
4. Disconnect the pedal connector, measure the pin voltage, and there is no abnormality in the power supply 5V, signal wire and ground wire. The fault of replacing the accelerator pedal has not been solved.
Note: the accelerator pedal signal is connected with a pull-down resistor in the ECU. When the test signal line is disconnected, the voltage is 0V, which is different from other sensor signal lines. Special attention should be paid.
5. At this point, we can only check the circuit. Disconnect the ECU connector, and there is no abnormal phenomenon of water inflow and needle withdrawal. To be safe, plug copper wire on the pin to prevent virtual connection, and the fault remains.
6. Disconnect the vehicle chassis harness and body harness connector. If the connector is corroded by water, clean it with alcohol, dry it and load it. The fault is completely solved of accelerator pedal signal.
The driver’s driving intention is transformed into an electrical signal through the sensor and sent to the ECU to quickly and accurately control the power output of the engine. It has the following functions: torque control (fuel control); Idle speed control (high and low idle); Deceleration oil cut-off control; Limp home control.
Working principle of electronic accelerator pedal: the sliding resistance accelerator pedal position sensor works on the principle of voltage dividing circuit, and the ECU supplies 5V voltage to the sensor circuit. The accelerator pedal is connected with the brush of the sliding rheostat inside the sensor through the rotating shaft. When the brush position of the pedal position sensor changes, the voltage between the brush and the grounding terminal changes, and the pressure circuit inside the computer converts the voltage into the position signal of the accelerator pedal of accelerator pedal signal.