As the weather turned cooler, everyone’s clothes became thicker and thicker, and the heating was raised at home. Does our car also turn on the heating mode? Next, the fault case we share with you is the fault related to post-processing heating. The fault is simple but experience is important. I hope this case will bring you some inspiration in this winter. At the same time, I would also like to thank: Master Rongbin of Cangzhou City for the material provided of vehicle torque limit!
Model: Foton Daimler ETX
Engine: Cummins
Computer board: Cummins cm2880
Post treatment: Cummins Ecofit urea pump
Fault phenomenon: the vehicle fault light is on, urea is not burned, and the engine torque is limited!
Fault description: the owner reported that the instrument fault light of the car was on, the aftertreatment urea was not consumed, and the power of the engine decreased significantly of vehicle torque limit.
1. Start the vehicle according to the situation described by the owner and find that the engine fault light is always on. After entering the engine system with the decoder, read the two fault codes “1683 aftertreatment 1 diesel engine exhaust treatment fluid filling heater voltage at normal value” and “2765 injector barcode out of calibration” of vehicle torque limit
2. According to the analysis of the read fault code, “2765” is a historical fault and will not cause the possibility that the vehicle does not consume urea and limit torque. “1683” is an aftertreatment related fault code and an important aftertreatment heating fault. In this cold winter, if there is a problem with urea heating, how can the vehicle consume urea? According to the “1683” fault code prompt, there is a problem in the heating part of the urea tank, and the heating of the urea tank is controlled by the “heating solenoid valve” (ECM controls the flow direction of the coolant by controlling the on-off of the solenoid valve and heats the urea tank through the coolant) of vehicle torque limit
3. After troubleshooting, the problem is all directed to the heating control solenoid valve. Find the heating solenoid valve and use a multimeter to measure its resistance value of 3.4 Ω. You can see here that the solenoid valve has been damaged (the resistance value of normal heating solenoid valve is about 40 Ω)
4. Replace the new solenoid valve and measure that the resistance of the new solenoid valve is 41.7 Ω. After replacing the new solenoid valve, use the decoder actuator to test and drive the solenoid valve. It is found that it still cannot be driven, and the fault code still exists.
5. use the decoder to control the solenoid valve and use the test lamp to measure the control line. It is found that the test lamp is not responding. To find the relevant circuit diagram on the WeChat official account of the carpenter online, to measure whether the two wires of the solenoid valve are connected to the ECM, and when measuring the control line, it is found that there is resistance and it does not work. It can be determined that there is a problem in the solenoid valve control harness. The next step is to find the fault point. Finally, it is found that the control circuit of the solenoid valve is open! (see the figure below for the fault point) install a new heating solenoid valve and repair the harness, and then solve the fault!
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