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Electrical system 33
9-5
E363D028
Rain sensor
The rain sensor is a control module with its own
logic. It is NOT connected to the bus and,
therefore, will not generate fault codes or
communicate with Tech 2. The sensor is located
on the windshield in front of the rear-view mirror.
It is pressed against the inside of the windshield
and secured with two clips. A silicone cushion is
located between the sensor and the windshield
to follow the shape of the windscreen. The rain
sensor is protected by a cover. The cover can be
removed using tool 82-93-474.
When activated in automatic mode (position 1),
the wipers will make one reference stroke to
calibrate the sensor while the windshield is clear
and to inform the driver that the sensor is
activated. If the ignition has been turned off, the
sensor must be reactivated by moving the stalk
switch to position 0 and then back to position 1.
The rain sensor consists of two LEDs that
generate infrared light, two photo diodes that
receive light signals, and one photo diode to
distinguish between night and day.
The sensor controls automatic mode (position 1),
high speed (position 3), and wash/wipe (position
4).
Function
A night/day photo diode measures the external
light and informs the rain sensor so it can adapt
its sensitivity. The system recognizes that the
driver needs increased sensitivity in darkness.
The light sensors generate infrared light that is
refracted at a certain angle in the surface layer of
the windshield if there is no snow or rain on the
windscreen. When there are raindrops or
snowflakes on the area that the sensors cover,
the light will refract at a different angle.
The photo diodes receive incoming light and,
from this information, the microprocessor can
determine whether the rain sensor should
activate the wipers.
Operation in special conditions
• Tunnels - When the car is driven through a
tunnel, the wipers will be interrupted. Outside
the tunnel (after the interruption), high speed
can be activated rapidly if the sensor detects
any drops of water.
• Splash - If a shower of water washes over
the windscreen, high speed will be activated
until the water has been wiped away.
• Worn wiper blades (smearing) - Worn or dirty
wiper blades will form a fast-drying film of
water that covers the sensor surface. The
sensor will prevent unnecessary wiper action
and excessive wear of the wiper blades.
• Dirt function - The wiper blades will not be
activated if the sensor detects a dirty
windscreen. The driver will have to wash the
windshield first.