哈密大众宝来轿车维修，发动机出现无法启动
一辆采用1. 6L发动机和手动变速器的大众宝来轿车。（哈密大众宝来电信宽带维修）该车原来运转正常，可冲洗过发机后出现无法启动的故障。（哈密大众宝来电信宽带维修）
故障诊断：因为该故障是冲洗发动机后才出现的，所以首先就用压缩空气将有关电器元件、导线连接器、高压线和火花塞吹干后试车，故障依旧。（哈密大众宝来电信宽带维修）接通点火开关，测量空气流量传感器的电源端子，竟然没有5V电压。（哈密大众宝来电信宽带维修）将点火开关置于启动挡，发现喷油器偶尔会工作一下，火花塞也偶尔跳一次火，由此基本上断定发动机控制单元输出电源有误。（哈密大众宝来电信宽带维修）检查发动机控制单元的电源端子和搭铁情况，都正常，也没发现发动机控制单元有进水的迹象。（哈密大众宝来电信宽带维修）
用元征431ME故障检测仪读取故障码，显示有3个故障码，分别是：节气门控制单元J338信号错误；加速踏板位置传感器G79信号错误；发动机转速传感器G28无信号输出。（哈密大众宝来电信宽带维修）用故障检测仪清除故障码，发现节气门控制单元J338信号错误和加速踏板位置传感器G79信号错误，故障内容无法清除。（哈密大众宝来电信宽带维修）仔细检查节气门控制单元和加速踏板位置传感器，发现加速踏板位置传感器上有水迹。（哈密大众宝来电信宽带维修）接着查找水是从何处漏进来的。（哈密大众宝来电信宽带维修）原来该车曾加装过防盗器，该防盗器的喇叭线就是从加速踏板上方牵出去的，当冲洗发动机时水顺着防盗器喇叭线滴到加速踏板位置传感器内，导致加速踏板位置传感器发出错误的信号给发动机控制单元。（哈密大众宝来电信宽带维修）
拆下加速踏板位置传感器，并撬开其边盖后用压缩空气将其内部水分吹干净后试车，启动正常，故障彻底排除。（哈密大众宝来电信宽带维修）
A Volkswagen Bora with 1.6L engine and manual transmission. (Beihai Volkswagen Bora car maintenance) the car was in normal operation, but it failed to start after washing the engine. (Beihai Volkswagen Bora automobile maintenance)
Fault diagnosis: since the fault occurs only after the engine has been washed, the first step is to dry the relevant electrical components, wire connectors, high-voltage wires and spark plugs with compressed air and run the test. The fault is still the same. (Beihai Volkswagen Bora car maintenance) turn on the ignition and measure the power terminal of the air flow sensor. There is no 5V voltage. (Beihai Volkswagen Bora automobile maintenance) put the ignition switch in the start position, and found that the fuel injector occasionally works, and the spark plug occasionally jumps once, so it basically concluded that the output power of the engine control unit is wrong. (Beihai Volkswagen Bora automobile repair) check the power terminal and grounding condition of the engine control unit, they are all normal, and there is no sign of water in the engine control unit. (Beihai Volkswagen Bora automobile maintenance)
Read out the fault code with the element 431me fault detector, and there are three fault codes displayed, which are: the signal error of throttle control unit j338; the signal error of accelerator pedal position sensor g79; no signal output of engine speed sensor G28. (Beihai Volkswagen Bora automobile maintenance) using the fault detector to clear the fault code, found that the throttle control unit j338 signal error and the accelerator pedal position sensor g79 signal error, the fault content can not be cleared. (Beihai Volkswagen Bora automobile repair) carefully check the throttle control unit and accelerator pedal position sensor, and found that there is water trace on the accelerator pedal position sensor. (Beihai Volkswagen Bora car maintenance) then find out where the water leaks in. (Beihai Volkswagen Bora automobile maintenance) originally, the car was equipped with an anti-theft device. The horn line of the anti-theft device was pulled out from the top of the accelerator pedal. When washing the engine, the water dripped into the accelerator pedal position sensor along the horn line of the anti-theft device, causing the accelerator pedal position sensor to send an error signal to the engine control unit. (Beihai Volkswagen Bora automobile maintenance)
