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A mileage of about 100 thousand km, equipped with M104 engine and automatic transmission, chassis type W140 Mercedes Benz S320 car. The car malfunction is: after a body repair operation, the engine is unable to drive. After receiving the vehicle: confirm the fault symptoms, the engine turns, but it can't work. The dashboard has a "Error" message flashing, indicating that the fault is related to the burglar function. The connection diagnostic instrument is self diagnosed, and the engine system has two fault codes. The contents are as follows: "P1580, throttle actuator (M33) fault"; "P1570, engine control module's driving authorization data error". It can be seen from the maintenance experience that if the electronic throttle is poor or circuit breakage, as long as the accelerator pedal is used to start the engine, the engine can work, only the symptoms of failure to speed up and fail to maintain the idle speed will appear. The fault code P1570 shows that the vehicle has the driving power control function. In the process of starting, if the driving authorization control module (DAS control module) does not receive the correct programming data of the ignition key, the starting signal will be sent to the engine control module and the engine can not be moved. Therefore, the driving license system is more likely to fail. Query driving authorization system (DAS 2B fault information, there is a fault code, the content is "B1703, the transmitter is damaged, the fault is present". The transmitter is the internal chip of the ignition key, which has the function of "one action jump code", and the encoded data is stored in the chip. Check the data flow and know that the No. 30 power is connected, but the driving authorization system is in a locked state. Locate the DAS control module below the dashboard and measure its power cord and ground wire, normal. The ignition switch lock has an annular coil (antenna), which is used to transmit the ignition key encoding data to the DAS control module. The measuring ring coil resistance is 30 Omega, normal. Replace the ignition key, and the failure is completely eliminated. The Mercedes Benz driving authorization system can be divided into the following structural forms: