A concrete lifts can not work, the specific phenomenon: the left front door on the glass lift combination switch can not control the other three door glass, but the doors of the glass lift Switch can control the glass lift. According to the customer to reflect, for the maintenance of this car, had several repair shops in the local did not solve the problem, I hope this repair can be troubleshooting.
    The car comfort system is different from the old POLO. The old POLO's comfortable system uses CAN-bus bus two-wire connection, if there is a high line or low line break, will not affect the work of the entire comfort system. The new POLO comfortable system internal communication with the LIN-bus bus single-wire connection, if the LIN-bus circuit, the comfort system control signal will be affected. In addition, the old and new POLO each door of the control unit is to share a fuse to provide positive power supply. The new POLO each door and between the comfort system control unit between the exchange of information, that is, rely on LIN-bus bus, so the car is likely to appear in the fault above the line.
    Clear the basic working principle, maintenance will have a direction. Since the other door switch can control the lift of their respective glass, that positive and negative power supply is no problem, the fault should be out of the main switch, line or comfortable system control unit above. The first thing to exclude is the circuit failure.
    Using the multimeter to measure the line, it is found that the LIN-bus between the driver's side door control unit and the other door control unit and the comfort system control unit is not available and the measured resistance value is infinite. While the comfortable system and the other three doors between the LIN-bus normal, it appears that the fault is above this communication line.
    Along the direction of the layout of the line inspection, in the left front door and A column connection plug found the problem - the plug has been serious corrosion. The original car has been installed burglar alarm, the plug on the dust cover to damage, resulting in poor sealing. Due to rain or car wash and other reasons leading to plug the water here, a long time to produce oxidation, resulting in the left front door control unit and other control unit of the comfort system communication between the interruption. Wait until the repair found this point, the plug inside the metal connector has been oxidized no.
    As the cost of replacing the wiring harness is too high, the customer does not agree to replace, so the maintenance staff with a special harness repair tool to repair the damaged joints, installed after the test found that the fault completely ruled out.