BMW 730Li without electricity generator

        BMW N52 engine model F02 730Li sedan. The car does not appear generator power during normal driving, the oil level can not detect other failures.
        Troubleshooting: After receiving the car, that the car can not be started again after the stop, lap battery, start the car and driven back to the factory and found that the car can not detect the oil level. Connect diagnostic and found several fault code. Delete query again, only BSD bus communication failure.
        According to the circuit diagram that has a generator (G6524) on this car BSD bus, oil condition sensor (B62540), electric mb sd connect c4 coolant pump (M6035). Find bus (36,37,42 port) at the plug in the engine computer, measured with a multimeter, no voltage. When voltage is 8V will be open around the ignition switch under normal conditions. Unplug the unit were on the bus (but must ensure that there is always a component connected to the bus), but no matter which one unplug, never on the bus voltage output, the larger the computer to determine the possibility of damage. Measured with a multimeter, the bus is shorted to ground. Open the front of the engine computer shell, found associated with BSD components are in the back of the PC board. Difficult to open the back of the shell, only the back of the BSD associated components corresponding parts cut (to find a scrap computer, open, determine the location of the BSD components related to find the exact location, then put the computer in need of repair with wheels cut). Pin down the measure, found the bus to enter a BSD model 27u transistor, through the transistor into a model for the 1020 IJA 8 pin chip inside. By querying the data and found that IJA 1020 is a communication piece. Measuring transistor, breakdown. In order to successfully coefficient highs, decided to replace the communication piece together with the transistor, then contact the supplier of electronic components shipped. After receiving element refitted, test, the voltage on the bus. When all components are plugged on the bus, and then measured, not any voltage, indicating which parts are still on the bus problem. Unplug the individual components one by one, disconnect the generator when the voltage normal. So they changed the generator, start the vehicle icom a2 properly. Can also be displayed on the central display normal oil level, and measuring the generator voltage is normal. Clear fault codes, BSD bus communication fault code is not reproduced.
         Service Summary: The analysis of the case through the maintenance, we can see that, for the maintenance of high-end models, the key is to identify the root cause of the problem, not blindly replacement assembly parts. High-end models for fault diagnosis of electrical faults, 思路尤 important, while refined inspection of electronic components is also quite important. Since the electronic control system for more precise calculation of information but also to control the increasingly high demand, so the traditional service will become history. Change the traditional maintenance concepts, establish a correct concept of scientific thinking is a prerequisite for a new generation of auto repair person.
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