There are 2003 Honda accord 2.4 cars with mileage exceeding 220 thousand km. The car owner reflects: the car has a long light. Fault diagnosis: first, let the owner know more about the recent use and maintenance of the vehicle. According to the car owner, this car started a few days in the morning after the start of the vehicle when the whole car did not have electricity, then found the maintenance personnel to replace the battery, starting to find that the light has always been bright, then after the switch a few times before the light all normal. When I picked up the car, I found that when the light was switched on and off, sometimes the high beam was always on the bright side, and was not controlled by the headlight switch. Carefully inspected the peripheral line, light switch, found that the near, near light light bulb has been changed, all changed into the 100W bulb (the original car bulb is 60W), so it was thought that the power burned down the light switch, then replaced the light switch assembly and the original factory standard 60W bulb, after several tests, it was found that everything was normal. After delivery to the owner. Four days later, the owner of the car called, saying that the car had no electricity like a few days ago. Then I took a spare battery and started back to the repair factory when the car was started. According to the car owner, the car will also appear in the evening. After careful analysis of the circuit diagram, the light signal is sent to the relay module through the combination lamp switch No. 1 pin. The relay module will send the fuse from the 22 fuse wire to the 1 and 6 fuse (left and right near light) through the internal relay. The light signal is sent from the combination lamp switch 4 pin to the MICU (multichannel integration) through the CAN bus. Control device) 27 feet, and then send the relay module through MICU to the relay module to carry out the whole dimming, meeting and running lights control of the CAN. It is therefore speculated that the high light may be directly related to the damage of relay control module. Then it is found that the remote light is extinguished after the relay module is tapped at the light of the long light, and it is determined by repeated tests that the relay contacts are attached to the relay contacts. Since the accord 2.4 has a light delay control, the owner has a habit of never turning off the lamp after stopping at night, which causes the phenomenon of the long light light to run out the battery. Because the relay can not be replaced alone, the entire relay module is replaced and troubleshooting is replaced. Maintenance summary: after dismantling the defective components, it is found that the contacts inside the high light relay are ablated due to the excessive current. To remind all colleagues to refit the lighting system, do not add more than the prescribed large power bulbs in the original harness of the original car, so as not to cause the circuit, switch contacts overheating, even the serious consequences of fire. Fault review: the case elimination step is to inquire about the failure phenomenon - check the exception and deliver the user a failure phenomenon again - reconfirm the cause of the failure once again. The first time we entered the factory, we only analyzed some reasons, and replaced the lamp of the disaster lamp (more than the specified high-power bulb). The analysis of the second plant was very comprehensive, and the long light relay was replaced (due to the use of large power bulbs before the contact of the relay was ablated). Finally, the author reminds the refitting shop that it is reasonable to change the vehicle. When the vehicle is repaired, especially the new car, the maintenance personnel should tighten a string in the mind. First, ask and check whether the vehicle is modified or not, and then use the maintenance manual and circuit diagram to analyze all the causes of the failure so as to avoid multiple repairs to the same kind of fault. If the fault car is repaired in a comprehensive car repair plant, the maintenance staff may read the user's manual because of the lack of maintenance manuals and circuit diagrams. If you know to send a repair car to have a modified (plus) equipment, we should carefully check the unreasonable parts of the artificial change part, use analysis, reasoning and other methods to remove the false and save the truth and find the source of the disease.