9-3 (9440) V6-2.8L Turbo (2008)
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communication cable.
When the rain sensor detects water on the windscreen it sends information to the REC (701). The REC transmits a "Rain sensor requests wiper" bus
message with one of the following values:
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OFF
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LOW
^
MEDIUM
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HIGH
The value (OFF/LOW/MEDIUM/HIGH) that is sent depends on the amount of water on the windscreen and the sensitivity that is set. The bus message is
used by the UEC (342) to activate the windscreen wiper motor. The windscreen wipers can be activated at low speed, high speed or for single sweeps. If
the signal from the rain sensor is missing, the UEC initiates continuous wiping.
The rain sensor is activated by moving the stalk switch, located to the right of the steering wheel, to the automatic position, equivalent to the position for
intermittent wiping on cars without rain sensor. When the rain sensor is activated, the wipers make a single sweep for reference, partly to calibrate the
system when the windscreen is clear and partly to inform the driver that the system has been activated. If the car is started with the stalk switch in the
automatic position, the switch must first be moved from this position, then returned to the automatic position for the rain sensor to be activated.
The rain sensor takes over control of the windscreen wiping from the UEC. The system changes between no wiping, single strokes and continuous
wiping depending upon how much snow or water is on the windscreen. With diminishing light the sensitivity of the rain sensor increases.
Function under different conditions
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When driving through a tunnel, the wipers pause to quickly be able to switch to high speed if necessary.
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When a large amount of water flows over the windscreen, e.g. when meeting another vehicle, high speed is activated until the water is gone.
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If the wiper blades are worn or dirty, a thin film of water can build over the sensor surface. The rain sensor detects this and avoids activating the
wipers unnecessarily.
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When the rain sensor detects that the windscreen is dirty, the windscreen is cleaned before the wipers are activated.
