【Failure phenomenon】
A 2005 BMW 530 with E60 chassis and a driving range of 50,000km. The front windshield was cleaned without water spray, the glass washer spray did not work, and the wiper was normal. BMW Repair
【Fault Analysis】
Operate the wiper switch, the front wiper works normally, but the water spray switch is operated, the wiper works, and there is no water spray, indicating that the switch is good, the headlights are cleaned, and the headlights are sprayed normally. But when operating the glass spray water, the water spray motor has no response. When measuring the water spray motor, there is no voltage reached and the grounding wire is normal.
As can be seen from the schematic circuit diagram (Figure 1-27), the working principle of the cleaning pump is: the steering switch module receives the water spray switch signal and sends the signal to the gateway module, which transmits the signal to the vehicle body through the network CAN-BUS The control module sends a signal from the body control module to control the action of the washing pump. Since the front wiper works normally, it indicates that the public circuit and system are not faulty. The fault point is in the body control module ZGM and the line to the pump motor. Measure the line from the body module to the cleaning pump motor. The line is normal and there is no open circuit fault. If the motor voltage is directly applied, the cleaning pump motor can also work, indicating that there is no problem with the motor and the line. The problem is in the body module.
Use Launch X431 diagnosis to read the fault code of the control unit. There is no fault code in each system, indicating that the system is normal.
The component test function in the body control unit found that the test cleaning and water spray function is normal and the water spray motor can spray water, but when the wiper switch is used to control the water spray, the water spray motor does not operate, which eliminates the fault on the motor circuit.
Since there is no problem, what caused the body module to cut off the water injection motor?
Since the body control unit does not have a fault code, it means that all sensors and signals are normal, and the control unit normally cuts off the water spray function. Since it is a normal cut-off function, the body control unit will transmit relevant information on the network through the network, and other The system will also get information. Ford DIY
Observe the instrument display, there is no abnormal display. This car has a central information display system CID display. Click to enter the after-sales service system. There are two menus: maintenance requirements and vehicle information. Click on the vehicle information, the display shows a message that the wiper cleaning fluid is missing. Check the water volume of the spray bottle. Most of the pots and the sensor are good. Fill up the kettle, confirm on the display, return, check again, there is no water shortage information. Press the water spray switch, the water spray motor works and the fault disappears.
【Troubleshooting】
Clear the fault information of the central information display, the water spray is normal, and the fault is eliminated.
【Precautions】
Because the central information display center has stored fault information and has not been cleared, the information center transmits the information to the body control unit through the network system, and the body control unit blocks the water spray function.
