Precautions for Troubleshooting of Electronically Diesel Engine
Posted: 2014-12-03 20:59:38 Hits: 2661
As is known to us, with the development of the national requirement for the pollution discharge, EUROⅢ (National Ⅲ) engines are used more widely in the special heavy vehicle. Because electronic-controlled engine technology content is higher, maintenance personals are required higher in technical level, especially in circuit, electrical appliances, electronic technology and computer control. It’s far from enough to do some troubleshooting according to the past experience. Modern heavy-duty truck maintenance personnel, therefore, must rapidly improve their maintenance skills and develop their technical level, especially for the electronic circuit and computer technology. Certain scientific methods for the troubleshooting of electronic-controlled engine should be grasped. We respectively introduce scientific methods of fault checking problems as followed that should be paid attention to while troubleshooting for electronic-controlled engine.
1. Whether the engine is running, as long as the ignition switch is turned ON (ON), you must never disconnect the ECU, sensors and actuators because any coil self-induction effect can produce high instantaneous voltage, making ECU and sensors be badly damaged. Therefore, we should develop the habit of pulling, inserting ECU and sensors, actuator and connector clip under the conditions of closed ignition switch (OFF). Otherwise, it tends to cause consequences new faults, with old faults not being ruled out. Moreover, removing the sensor connector plug during engine operation or when the ignition switch is connected (ON) can also bring artificial fault code to the ECU (a false code), which will interfere maintenance personnel to correctly judge and troubleshoot.
2. The power supply cord of computer should be turned off before doing arc welding for vehicle equipped with electronic control system, to avoid computer damage caused by high voltage. The overall battery wire should be removed while welding.
3. It should be especially careful while doing the repair operations near the ECU or sensors, to avoid damaging these electronic components.
4. The fuel system should first be unloaded before disconnecting any oil way. When maintenance the oil system, don’t smoke and stay away from open flame. Due to that fuel pressure in the electronically controlled high pressure common rail fuel injection system is extremely high, it is absolutely not allowed to use the method of removing fuel injector connector to implement "broken cylinder" in the inspection of the engine, or the jet of high pressure fuel will directly cause bodily harm.
5. All the failure information(code) stored in the computer will be removed after removing the battery cathode by iron wire, as a result, if necessary, the failure information should be read before removing the battery cathode by iron wire.
6. Remove the battery and then install. Make sure the ignition switch and other electric equipment switch are placed in the off position.
7. Remember that the power supply system in the electric motor car is adopted by the negative iron, so it is important to pay special attention to that the positive and negative poles cannot be pick up against in the installing.
8. Radio stations with over 8W power cannot be installed in the car. If necessary, the antenna should be as far as possible away from the ECU, otherwise it will damage the circuits and components of ECU.
9. When install or remove the ECU, first make yourself take the iron body, otherwise, the body’s static electricity will damage the ECU circuit.
10. The electric control system should avoid being damaged because of overloading on the maintenance of electric control system. The working current of sensor and ECU are usually small in the electric control system, therefore, the load capacity with the corresponding circuit components is also small. For the use of testing tool with less input impedance in the troubleshooting, it may make the components be overloaded and damaged due to the use of testing tools components. Thus, we should pay attention to the following:
① Test lamp cannot be used to check the sensor of electric control system and control unit of ECU (including the terminal examination).
② Generally analog multimeter cannot be used to check resistance of the electric control system. Use high impedance digital multimeter or electric controlled special detecting instrument.
③ It is resolutely banned to check the circuit by the way of taking iron for fire or removing the wire in cars with electronic control system.
11. Do not flush the ECU control unit and other electronic devices, and pay attention to the protection of the ECU control system, avoiding disorder of circuit boards, electronic components, integrated circuit and sensors because of damp.
12. Generally, do not open the cover plate of ECU, because most of electronically controlled engine failure are external equipment failure. The failure of ECU is generally less, it should be tested and maintenanced by professional personnel even the ECU is defective.
1. Whether the engine is running, as long as the ignition switch is turned ON (ON), you must never disconnect the ECU, sensors and actuators because any coil self-induction effect can produce high instantaneous voltage, making ECU and sensors be badly damaged. Therefore, we should develop the habit of pulling, inserting ECU and sensors, actuator and connector clip under the conditions of closed ignition switch (OFF). Otherwise, it tends to cause consequences new faults, with old faults not being ruled out. Moreover, removing the sensor connector plug during engine operation or when the ignition switch is connected (ON) can also bring artificial fault code to the ECU (a false code), which will interfere maintenance personnel to correctly judge and troubleshoot.
2. The power supply cord of computer should be turned off before doing arc welding for vehicle equipped with electronic control system, to avoid computer damage caused by high voltage. The overall battery wire should be removed while welding.
3. It should be especially careful while doing the repair operations near the ECU or sensors, to avoid damaging these electronic components.
4. The fuel system should first be unloaded before disconnecting any oil way. When maintenance the oil system, don’t smoke and stay away from open flame. Due to that fuel pressure in the electronically controlled high pressure common rail fuel injection system is extremely high, it is absolutely not allowed to use the method of removing fuel injector connector to implement "broken cylinder" in the inspection of the engine, or the jet of high pressure fuel will directly cause bodily harm.
5. All the failure information(code) stored in the computer will be removed after removing the battery cathode by iron wire, as a result, if necessary, the failure information should be read before removing the battery cathode by iron wire.
6. Remove the battery and then install. Make sure the ignition switch and other electric equipment switch are placed in the off position.
7. Remember that the power supply system in the electric motor car is adopted by the negative iron, so it is important to pay special attention to that the positive and negative poles cannot be pick up against in the installing.
8. Radio stations with over 8W power cannot be installed in the car. If necessary, the antenna should be as far as possible away from the ECU, otherwise it will damage the circuits and components of ECU.
9. When install or remove the ECU, first make yourself take the iron body, otherwise, the body’s static electricity will damage the ECU circuit.
10. The electric control system should avoid being damaged because of overloading on the maintenance of electric control system. The working current of sensor and ECU are usually small in the electric control system, therefore, the load capacity with the corresponding circuit components is also small. For the use of testing tool with less input impedance in the troubleshooting, it may make the components be overloaded and damaged due to the use of testing tools components. Thus, we should pay attention to the following:
① Test lamp cannot be used to check the sensor of electric control system and control unit of ECU (including the terminal examination).
② Generally analog multimeter cannot be used to check resistance of the electric control system. Use high impedance digital multimeter or electric controlled special detecting instrument.
③ It is resolutely banned to check the circuit by the way of taking iron for fire or removing the wire in cars with electronic control system.
11. Do not flush the ECU control unit and other electronic devices, and pay attention to the protection of the ECU control system, avoiding disorder of circuit boards, electronic components, integrated circuit and sensors because of damp.
12. Generally, do not open the cover plate of ECU, because most of electronically controlled engine failure are external equipment failure. The failure of ECU is generally less, it should be tested and maintenanced by professional personnel even the ECU is defective.
