After 2000, the Mercedes-Benz W220S320 series of wiper control system in addition to retaining the normal function of wiper control before 1999, the addition of the following features:
    1, according to the speed and raindrop sensor signal control, when the wiper position in the "1" block and "2" block, the automatic control began to function, when the vehicle speed below 5km / h (vehicle speed signal sent by the left front wheel speed sensor To the instrument panel, and then to the SAM (FR) control unit), SAM (FL) control unit to control the wiper motor intermittent operation, the frequency according to the raindrop sensor signal control wiper motor [raindrop sensor signal to the roof light panel control module (N70) , And then passed to the left front SAM control unit, the control unit signals are transmitted through the computer network transmission (CAN) transmission]. Car maintenance and maintenance network
    2, the use of CAN-BUS connection, the control unit will control the command code, sent to the fixed "H", "L" circuit, this line can simultaneously transmit multiple signals, the signal contains the address code plus information code , And the information code is decoded, converted to available control instructions.
    3, SAM control unit, N10 / 6, N10 / 7 is divided into left and right 2 control units, respectively, with fuse, relay box, installed in a whole, receive wiper CAN signal, control relay work.
    4, wiper, windshield water spray with heating function.
    5, the use of automotive temperature sensor sensor outside the temperature, the signal sent to the right before the SAM control unit, the CAN connection to the left before the SAM control unit to control the wiper heating temperature.
    Troubleshooting Case:
    Symptom: An annual output of 2000 Mercedes-Benz W220S320 sedan, the user reflects the car wiper the first block (intermittent block) can only move once, no longer continue to work (that is, no intermittent work), the other block normal. The wagon control of the car is completely changed by the switch signal control relay mode, which is controlled by the CAN-BUS network signal transmission control between the control units.
    Troubleshooting: This wiper system consists of a wiper switch (combination switch assembly S4), a combination switch control unit (N80), a SAM, a raindrop sensor (using a photoelectric sensor), an external temperature sensor, a water spray motor and a windshield nozzle (With heating function). The control process of the wiper motor is shown in Fig. The possible causes of intermittent block failure are: damage to the combination switch intermittent switch, damage to the combination switch control unit N80, damage to SAM (FL), damage to the wiper relay (1, 2 block), failure of the raindrop sensor and its wiring, and Roof panel control module failure.
    With the fault diagnosis instrument "repair car king" Mercedes-Benz expert card on the SAM (FL) and head panel control module to check, did not find the fault code. As the LO and HI gear are working properly, combined with wiper system working principle analysis, I suspect that the failure may occur in the head panel control module or raindrop sensor and its line. First check the rain sensor, with a multimeter to measure the raindrop sensor terminal voltage 1 and the resistance between the No. 3 and the body are within the standard value; and then measure the SAM (FL) B2 voltage, found with high pressure water jet before the windshield or front windshield Glass no water, B2 terminal voltage has been about 2V, indicating that the raindrop sensor has been damaged. After removing the raindrop sensor, it was found that the raindrop sensor was pasted with double-sided adhesive. Ask the user, that the car was not long before the windshield glass crack appeared before the replacement of the front windshield glass. Before the replacement of the glass, the wiper every gear is working properly, but after the replacement of the front windshield has not been used wiper intermittent block, a few days before the rain with intermittent block only to find the above fault.
    At this point, the fault has been clear. After removing the double-sided adhesive on the surface of the raindrop sensor, attach the raindrop sensor directly to the front glass (also open the intermittent stop of the wiper), then sprinkle it on the front block with water and intermittently block the normal work. After checking the relevant information, that the vehicle's raindrop sensor must use a special adhesive paste on the windshield, can not use double-sided adhesive, or rain sensor can not sense the amount of rain.
    Finally, after the raindrop sensor with Mercedes-Benz special adhesive paste on the windshield, the troubleshooting.