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A BMW 730LI (E66) car, after the ignition switch, the tire pressure yellow warning lamp alarm, display on the display tire pressure alarm system failure, and can not carry the tire pressure reduction. Fault diagnosis: it is found that the tire pressure alarm system of the car is a European regulation. The principle of the alarm is that the CIM (chassis integrated module) determines the tire pressure by 4 wheel speed signals from the DSC (dynamic stability control system), but the non European gauge car is to determine the tire pressure through the wheel tire pressure. Using ISID to test, can detect CIM, can judge its communication is normal, that is, the power supply of CIM, and K-CAN are normal, but for the sake of insurance, it is still to detect the power and communication of CIM, to prevent the phenomenon of virtual connection. Connect adapter 612190 to measure the voltage between terminals 13 and terminal 1 on the wiring harness connector X10320, 12 V, and measure the terminal 16 and terminal 17. Referring to the circuit diagram, CIM and DSC have 4 signal lines to transmit the wheel speed signals of 4 wheels respectively. These signals are digital signals after DSC operation, so the voltage on the terminals 8, terminal 9, terminal 10 and terminal 11 on the connector X10320 is measured with the multimeter, which are 11.6 V, normal, no abnormal bypass and short circuit. Phenomenon. It can be judged that the CIM system has been malfunction. So CIM programming, but after programming, the tire pressure warning lamp is still on the alert, after the replacement of CIM trial run, the failure is still. The suspicion is that the data sent by DSC is not correct, so the DSC control module is programmed and found to be unable to program. This phenomenon seems to indicate that the fault is caused by the DSC control unit, but after the replacement of the DSC control unit, the result is disappointing and the warning lamp still calls the alarm. The failure to check here has entered a deadlock.