After the test, the fault is as described by the user. Under normal circumstances, when the car lights in the door control position, open the door car lights lit; the other hand, the car lights off. Connection fault diagnosis VAS5051 fault guidance, the system is no fault. Switch door test, dashboard door lights indicate normal. Maintenance personnel to find a circuit diagram for analysis. According to the circuit diagram, the front lighting of the car has three lines: one for the 30 fire line, controlled by the relay; one for the vehicle network control unit J519 control line; the other for the ride line. Switch in the normal lighting position when the current direction: 30 relay → car lights → gated switch → grounding. If you remove the key after closing the door and remote control lock or mechanical lock car, J519 will cut off the 30 fire line, the lights go out. Switch in the gated position, the current direction: 30 relay → car lights → gated switch → J519. If the four doors are closed, J519 output battery voltage high potential, the car lights at both ends of the same voltage, the lights go out; if there is a door open, the J519 output line low potential, the car lights lit.
    According to the circuit diagram to measure the car front lighting assembly, 30 FireWire normal, take the normal line, J519 control line for the low potential of the wire, this time four closed, dashboard door lights off. First check the J519 control unit fuse, fuse normal. It is inferred that there will be three cases: J519 internal fault is always the output line low potential, J519 before the circuit problems, or J519 after the line problems. For this maintenance staff to remove the J519 B plug, measuring the 11 feet to the front of the car J519 control line between the resistance is 0, the wire without breaking; measuring J519 control line and the resistance between the wire is actually 0 The According to the circuit diagram analysis shows that under normal circumstances J519 control line and the resistance between the wire should be ∞.
    Maintenance personnel carefully analyze the circuit diagram and found that from the J519 output control line has two, respectively, for the front of the car lights and car rear lights. Remove the rear of the car lights assembly, measuring J519 control line and the cable line resistance is infinite, it seems that the problem lies in this. After careful observation and found that the lamp seat at the J519 control line and the connection between the line together. Under normal circumstances, in the lampholder J519 control line and the assembly line assembly, the metal chip board is one, installed after the application of tools to cut it. The car also has cut the traces, but not completely cut.
    Will be completely broken parts of the adhesive, the test troubleshooting.
    Summary: As the vehicle uses the vehicle network control unit, when the control line of fire to the ground short, the vehicle network control unit will take protective measures. If the circuit is still a separate form of circuit for the idea, may be detours. If the lamp is damaged by J519, replace the light bulb or not, as long as the light switch off and then re-open will return to normal. Can be seen, modern car technology in the continuous development, we have to continue to learn.