Failure phenomenon: a 2007 annual production FAW - Volkswagen Magotan 1.8T sedan, mileage of 37,000 km. The user complains about the left side of the headlamp switch EPB electronic mechanical parking system button E538 press does not work, and the shift lever next to the AUTOHOLDE540 button press did not respond, while the instrument on the yellow parking lights K213 light. This fault occurs occasionally, after the failure, the vehicle driving a distance fault will generally disappear, when the EPB button back to normal, AUTOHOLD button also returned to normal.
    Check the analysis: connect the fault diagnosis instrument VAS5052 for diagnosis, enter the address code 53 into the EPB system, the system stores two fault codes, respectively 02434 (left channel power supply control unit circuit / ground short circuit) and 02435 (right channel power supply Control unit open / short to ground). Simply put, the EPB system control program is issued by the E538 button signal, the signal is transmitted to the electronic mechanical parking control unit J540, and then issued by the J540 signal to the left rear parking brake motor V282 and right rear Wheel parking brake motor V283, the whole control process is relatively simple. AUTOHOLD Automatic parking function As a reinforcement function of the EPB system, the J540 is first collected by the J540 to meet the conditions of the AUTOHOLD operation. When the button E540 is pressed, the signal is transmitted to the J540, and the J540 passes the ABS control unit J104 to the left and right brakes Execute control.
    By the rear wheel parking brake circuit diagram can be seen, the fault code should be with the fuse SC29 and SC30 power supply of the two lines, but also with the rear parking brake motors V283 and V282 and related lines. If the fuses SC29 and SC30 are disconnected at the same time, the EPB control unit J540 can not communicate, and the ESP warning lamp lights up and disconnects any of the fuses, and the motor on the corresponding side does not work. First check the two fuse power supply (normal, are 12V), and then check the J540 T30 / 13 feet and T30 / 15 feet of power supply (normal, are 12V), which indicates that the wiring harness without circuit, the line resistance is less than 1.5Ω The And then check the V282 and V283 line conditions, T30 / 14 feet and T2an1 feet, T30 / 29 feet and T2an2 feet, T30 / 12 feet and T2ao1 feet, T30 / 27 feet and T2ao2 feet resistance between less than 1.5Ω, and no Short circuit or open circuit phenomenon. Check this, the motor V282 and V283 power line to determine no problem. Read the data stream, the data stream shows the EPB button E538 status error, so the maintenance staff decided to follow the circuit diagram to check the button between the button E538 and J540 line.
    Measure the J540 between the T30 / 20 pin and the button E538 T10i / 2 feet between the conduction, J540 T30 / 11 feet and E538 T10i / 5 feet between the conduction. T30 / 19 → T10i / 6 → T10i / 2 → T30 / 20; When the switch is pressed, the circuit moves: T30 / 18 → T10i / 4 → T10i / 5 → T30 / 11. AUTOHOLD button E540 when pressed, the circuit to: T30 / 11 → T6h / 5 → T6h / 4 → T30 / 9. After checking the E540 and E538 switch lines are normal, so decided to replace the J540.
    Troubleshooting: After replacing the J540, you need to make a number of settings, set up after the troubleshooting.
    Review Summary: The following need to change the settings after the J540 introduced.
    After replacing the J540, the ABS system and the EPB system need to be coded to see that there are multiple fault codes that have not been set in the two control units. The fault code can not be cleared because the J540 integrates the lateral acceleration and the longitudinal acceleration sensor , So the first sensor to set the basic. The implementation of 03-11-40168-04-60 on the G85 set, 03-11-40168-04-61 on the vertical acceleration sensor to the basic settings, 03-11-40168-04-66 on the brake pressure sensor set set. After the above settings, in the memory there are instrument K213 and drive anti-skid lights, 03-10-61-0 set, drive anti-skid lights off, and ABS control unit without fault storage. Instrument K213 or light, check the EPB system which has 01087 fault code (not the implementation of the basic settings), so the EPB system to guide the basic settings. After the above set is completed, all the vehicles back to normal.