A 2006 annual production of the public POLO strong 1.4L manual car, the owner reflects the car as long as the start of the engine or turn on the ignition switch, the wiper motor will always turn on the wiper switch gear adjustment does not work. The wiper motor will stop turning only when the ignition switch is turned off or the fuse of the rear wiper is unplugged.
    After the car to verify, the fault is indeed described by the owner. VAS5052 query with the control unit fault memory, no fault code found. The service personnel suspects failure in the circuit control section, the wiper switch, or the vehicle network control unit.
    According to the wiring diagram, the first detection of the wiper motor on the line and the wiper switch and power supply connection: 1 pin is the negative connection wire, the measurement is no problem. The No. 2 pin is drawn from the wiper switch T41 / 20 and is connected to the onboard network control unit (T18a / 15 pin), and there is no problem with the measurement. The No. 3 pin leads from the wiper switch T41 / 21 and is connected to the No. 2 pin of the wiper sprinkler, and there is no problem with the measurement. The No. 4 pin is the positive power supply of the rear wiper motor and is powered by the SB1 fuse controlled by the X-contact unloading relay, and there is no problem with the measurement. Measure the positive and negative pins of terminals 1 and 4, and the lines do not have short circuit and break between each other.
    Since the middle line did not find the cause of the failure, then the fault on the two ends of the line. Taking into account the rear wiper motor can run, then decided to remove the wiper switch. After removing the airbag, remove the steering wheel, unplug the wiper switch, and then turn on the ignition switch and find that the wiper motor is still running. Then unplug the T18a plug on the vehicle network control unit and find that the wiper motor stops running. When the wiper switch and the onboard network control unit T18a are unplugged, the rear wiper motor stops running, indicating that the fault must appear on the wiper switch or the onboard network control unit, and the line and rear wiper motor is not questionable.
    By turning on and off the wiper switch and the onboard network control unit, it is determined that the wiper motor has been operated because the vehicle control unit is damaged and an abnormal control signal is issued.
    Replace the vehicle network control unit, troubleshooting.