Description And Operation
The Body Control Module (BCM) manages the operation of the windshield wiper system.
The windshield wiper request may reach the BCM in two ways:
- Manual - the windshield wiper is activated when operated by the user.
- Automatic - the windshield wiper is activated automatically when it starts raining.
The control position on the right steering column stalk used for manual activation are:
| 1 | Windshield wiper low speed manual activation |
| 2 | Windshield wiper high speed manual activation |
Automatic activation can be selected by the user by setting the windshield wiper control position to one of the two initial positions. The user can set the rain sensitivity level of the automatic function by selecting position A or B.
| A | Rain sensor low sensitivity level |
| B | Rain sensor high sensitivity level |
The windshield wiper mechanism is located behind the cowl trim, just below the windshield.
The windshield wiper mechanism consists of a Local Interface Network (LIN) bus controlled electric motor (1) which operates the control linkage (2) of the two arms, to which the rest of the wiper linkage and wiper blades are connected.
| 1 | LIN bus controlled electric motor |
| 2 | Control linkage |
The feature of the electric motor is that it is controlled by electronics which can reverse the control linkage movement. In traditional windshield wiper mechanisms, the electric motor always turns the same way. The motion of the two blades is obtained by means of a cam present in the control mechanism.
In this case, the next-generation electric motor has a mechanism which does not always turn in the same direction but which cyclically reverses the sense of rotation without needing the motion inversion cam used in traditional mechanisms.
The main advantages of the system are:
- The blades are nearly invisible to the vehicle occupants when the blades are in home position.
- Larger wiping area. The system allows to set the motion inversion point very close to the A pillar of the windshield.
- Lighter weight of the system as a whole.
- Continuously controlled operating speed maintained in load conditions (wind force, variable friction).
Substantially, the electronics integrated in the motor can recognize the position of the arms instant by instant which allows for adjusting the rotation speed of the motor according to their position. When the blade approaches the motor inversion point, the rotation speed of the motor is reduced: this causes reduction of noise and less wear on the blade.
The electronics integrated in the motor can detect the presence of obstacles to arm movement (for example snow). An obstacle causes a higher current consumption. The system reduces the operating field of the arms to prevent damage when the current peak is detected.
The Body Control Module (BCM) manages motor activation by means of a dedicated LIN bus.
Windshield wiper wiring diagram
| 1 | LIN controlled electric motor |
| 2 | Steering column stalk controls |
| 3 | Windshield washer pump |
| 4 | Headlight washer system pump (top level headlights only) |
| 5 | Windshield washer fluid level sensor |
Windshield and headlamp washer system
The windshield washer system implements headlight washers only if the vehicle is fitted with top level headlights (Xenon 35W).
The system consists of a reservoir for the washer fluid, nozzle sprays and connection hoses. The reservoir is located behind the front left wheelhouse splash shield.
The BCM sends current to the windshield washer pump when the right SCCM stalk is pulled towards the driver.
| 1 | Headlight washer pump |
| 2 | Windshield washer pump |
| 3 | Headlight washer hose |
| 4 | Windshield washer hose |
| 5 | Fluid level sensor |
Light Rain Sensor Module (LRSM)
A rain sensor, located behind the interior rearview mirror, in contact with the windshield, can detect the presence of rain and, consequently, manage the cleaning of the windshield in accordance with the amount of water on the glass. In positions 1 or 2, the frequency of the windshield wiper strokes is automatically adjusted according to the amount of water on the windshield detected by the sensor: the frequency varies continuously from no stroke (windshield dry) to wiping at the second continuous speed (heavy rain).