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故障现象一辆帕萨特1.8T轿车,累计行驶里程约为13万km,车主反映该车不能起动着机,之前已在其他修理厂更换过3次发动机ECU,但时间不长故障现象又再次发生,于是委托笔者对该车做全面的电路检查和故障分析。故障诊断接车后首先验证故障现象。检查蓄电池电压为12.3 V,正常。起动机可以转动,但不能着机,拆下点火线圈并检查火花塞跳火,无火;检查油路,无油。检查发动机周围线路的连接情况,正常,重点检查曲轴位置传感器和凸轮轴位置传感器,正常。检查发动机ECU主熔丝,有12 V电压,正常;其他相关的熔丝也正常。连接故障检测仪,调得的故障代码为16989(电控单元存在着故障和不良)。于是只好拆下发动机ECU进行检修。为了进一步验证发动机ECU的故障出在哪里,让车主将之前3次更换的ECU取来拆开进行对比研究。该车采用了BOSCH的4B0906018CQ发动机ECU。拆下故障车上的ECU,连接好信号发生器,检查输出端的信
Fault phenomenon A Passat 1.8T sedan, the cumulative mileage of about 130,000 km, the owner reflects the car can not start the machine, before the other repair shop has been replaced 3 times the engine ECU, but the time is not long the fault phenomenon occurs again, So I authorize the car to do a comprehensive circuit inspection and fault analysis. Troubleshooting After the first car to verify the fault phenomenon. Check the battery voltage is 12.3 V, normal. The starter can be turned, but can not be turned on, remove the ignition coil and check the spark plug jump, no fire; check the oil, no oil. Check the connection of the line around the engine, normal, focus on checking the crankshaft position sensor and camshaft position sensor, normal. Check engine ECU main fuse with 12 V voltage, normal; other related fuses are also normal. Connect the fault detector, tune the fault code is 16989 (electronic control unit there is a fault and bad). So I had to remove the engine ECU for overhaul. In order to further verify the engine ECU fault out where, so that owners will be the first three replacement ECU taken apart for comparative study. The car uses the BOSCH 4B0906018CQ engine ECU. Remove the faulty ECU on the car, connect the signal generator and check the output signal