奥迪A8突然无法启动，检查好汽车搭铁点
Audi A8 suddenly failed to start, check the car tie point.
毛病现象
Fault phenomenon
一辆2013款德国原装奥迪A8(D4)轿车，搭载 CGW型发动机，行进路程2231km，客户反映昨晚低速行进中发动机俄然熄火，再也无法启动。
A 2013 German Audi A8 (D4) sedan with a CGW engine travels 2,231 km. Customers report that the engine suddenly stalled during the low-speed drive last night and could no longer start.
毛病诊断与扫除
Diagnosis and elimination of defects
将车拖进厂，测量蓄电池无电，用充电机对其充电，等充电完结，车辆能重新启动。衔接诊断仪检测毛病码，发现在所有操控单元均存储“电源电压过低，偶发”；在发动机、变速器、车门操控单元存储“无信号/通讯”。初步判断这些毛病码皆因蓄电池电量过低而被存储。
Pull the car into the factory, measure the battery is dead, charge it with a charger, and when the charge is over, the car can restart. Connection diagnostic instrument detects defect codes and finds that "low power supply voltage, occasional" is stored in all control units, and "no signal / communication" is stored in engine, transmission and door control units. It is preliminarily judged that all these codes are stored due to the low battery power.
使用诊断仪的毛病引导功用，经过查看发电机工作状况记载检测到“沟通发电机毛病，1次”，发生在 18:34。
Using the fault guiding function of the diagnostic instrument, after checking the working status of the generator, the fault of the communication generator was detected once, which occurred at 18:34.
问询客户在熄火前有无“充电正告灯报警、电量低需封闭音响的提示”，客户反映报警、提示都没有。
Ask customers whether there is a "charge warning lamp alarm, low power demand closed sound warning" before extinguishing, customers reflect the alarm, prompts are not.
再次查询毛病码（表1），“无信号/通讯”均发生在18点34分左右，“电源下限达不到”均发生在21点 9分左右，阐明先因“无信号/通讯”毛病导致发动机熄火，终才呈现电量低的状况。
Query the defect code again (Table 1), "no signal / communication" occurred at 18:34 or so, and "the lower limit of power supply can not reach" occurred at 21:9 or so. It is clarified that the engine stalled because of the "no signal / communication" fault, and finally showed a low power situation.
“无信号/通讯”毛病一般是操控单元正极供电线或接地线断路形成，本车多个操控单元在同一时间存储这个毛病码，应是由一个毛病点引发。阅览电路图，看到发动机、变速器、右前门J387、右后门J389等操控单元，正极供电是不同线路，而接地线共用右A柱下方的43号搭铁点搭铁。
The trouble of "no signal/communication" is usually caused by the break of positive power supply wire or ground wire in the control unit. The trouble code stored by several control units in the same time should be caused by a fault point. Reading the circuit diagram, we can see the engine, transmission, right front door J387, right rear door J389 and other control units, the positive power supply is different lines, and the grounding line shares the right A column below the 43 pick-up point.
拆检右 A 柱下方43号搭铁点，发现搭铁点接触不良，断开此搭铁点后电动电扇常转无法封闭。
Remove and check the No. 43 tie-in point under the right A pillar and find that the tie-in point is not in good contact. After disconnecting the tie-in point, the electric fan can not be closed.
紧固43号接地址螺栓，毛病扫除。
Tighten the No. 43 address bolt and remove the trouble.
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