In 2007, Shanghai Volkswagen Passat runs the 1.8T automatic car with a mileage of about 90 thousand km. User reflection: the car's turning light is not bright. After receiving the car: the maintenance personnel tried the car and found that the left and right steering lights were not lighted when the steering light switch was activated. However, when the emergency alarm light switch E3 with a steering relay is pressed, the left and right steering lights synchronously flicker. This indicates that the steering lamp relay and its output circuit are all normal, and the fault range is basically on the power supply of the steering lamp. Check the input of the fuse S2 (5 A) of the steering lamp with the 12V test lamp, and the test lamp is not lighted. The power of the steering light of Passat car is taken from the 75X power bus. The power bus is controlled by the ignition switch line 75 to control the unloading relay J59 (No. 370). According to the characteristics of the above circuit, the maintenance personnel will further determine the transmission of the power supply through other electrical appliances on the 75X power bus. Change the position of the air blower governor switch E9. All the blowers do not turn at all positions; open the wiper switch and the wiper; turn on the front light switch, the front light light but the front and rear fog lights are not bright. It can be seen that the 75X power bus does not output, but the 75 power supply has output, and it can be determined that the problem is in the unloading relay part. Pull out relay No. 370 from the fuse board of the instrument panel. When the relay is tested for monomer, it is found that the electromagnetic coil is open. Troubleshooting: replace relay No. 370, troubleshooting.