Rain sensor / Dusk sensor how to install Citroen C4

 

I have installed rain / dusk sensor in My Citroen C4. Sensor function is to turn on wipers in case of rain, regulate their frequency depending on the rain intensity, turn them off when the rain is gone. It is integrated as one device with dusk sensor that turn on and off lights depending on exterior brightness and turns lights during the rain.

Front windscreen should be dedicated for use of rain sensor, as it has proper color/transparency in place of sensor installation, and black paint to mask cables and sensor from outside.

I have installed rain sensor on regular windshield (not dedicated for sensor).

Sensor is fully optical device. It emits infrared light that reflects from the windshield on certain angel. Rain drops falling on windshield change angel of this reflection and lunch wipers.Sensors must be installed in area covered by wipers. There are at least four variants of rain sensor for C4 depending on windshield type (solar, anti reflective etc.)

The parts I needed

1) Rain sensor – brand new bought in Internet 25 Euro
2) Frame to hook rain sensor to the windscreen – bought in car windshield service – used, 2,5 Euro
3) Cover of the sensor + cover mounting – new from Citroen dealer 9 Euro
4) Switches under the steering wheel with “AUTO” option – used – 10 Euro
5) Adhesive foil black, primer black for windshields, glue for windshields, clean cloth, window washing fluid, gasoline
6) cable (I used computer network cable + plug from CD audio + some pins from computer power supply plug.
7) Lexia / Diagbox

1) Connecting cables

I have run cable from ceiling lamp under the lining through left roof column cover to board under the steering wheel (BSI 1). It is very easy, as there is a lot of space. I have connected cables to BSI 1 in following manner:

Pins on rain sensor plug are described from 1 to 4.

Pin 1 – 16V GR – pin 4 – PH2
Pin 2 – 40V BA – pin 24 – EH1
Pin 3 – MC46 – ground (same as for celling lamp and fotochromatic mirror that I have installed earlier)
Pin 4 – 40V BA – pin 26 – EH1

Plugs are situated as on the drawing below:

For each end of the cable it is nice to have pin from other plug that can be fixed on the wire before plugging it into car plug.

2) Change of switches under steering wheel.

Switch under steering wheel needs to be changed because it must have “AUTO” option on both ends. On the right to turn of and on automatic light steering, on the left to activate and deactivate automatic wipers control.

Pull steering well inside the car (steering wheel set mechanism), dismantle steering wheel column cover (2 screws), remove next 2 screws from switches module, take out 3 plugs and install new switches module in the same place.

Presence of advanced switches module must be confirmed via Lexia / Diagbox

3) Shadowing of the windshield and installation of holders.

Windshield should be darkened to cover sensor and cables from the outside.
Windscreens dedicated for the sensor have darker spots already on them, I had to do one myself.

I cut out shapes from transparent foil to have template. than i have painted windshield form the inside with black primer. That alone should be enough, but I added from the inside also black adhesive foil (except the spots where frame for sensor and cover mounting would need to be sticked – thouse were left with primer only). I did not painted area close to the sensor at once to do it precisely as later step.
With windshield glue I have sticked frame for the sensor (it is important to use right glue, as from regular glue windshield my brake due to aluminum stretching faster than glass, so it must be special glue). Cover mounting piece had it own glue already on it.

4) Installing sensor and covers

It is essential that sensor and the windshield are clean. If there is some fluf on the sensor surface remove it with wet cloth.

In C4 sensor is not sticked, it is set in place by the frame only. Placing the sensor please remember that there can be no any air left between it and window.
Do not touch transparent piece of the sensor with fingers.

5) Configuration

In Lexia / Diagbox it is necessary to activate sensor in at least four places, (sensor calculator presence, connection to BSI, wipers activation, turning lights activation by the sensor).

In Citroen software there is no option to calibrate sensor sensitivity. This option is available for example in software for Volkswagen group. I find it as big disadvantage.

All one can do is to “telecode” sensor via Internet, but account on Citroen server is required.

Functioning – after one quick test – automatic lightning works, wipers work slower and faster depending on amount of water pour in the windshield.

Rain sensors for Citroen and Peugeot do not have any adjustments option it is necessary to select specific type of sensor to specific type of wind shield. And there are around 10 types of sensors. From outside they differ with graphical symbol – 2 types of triangles, stars, 4 types of circles, square… I had to test several until I found one that is working just fine. Some were turning on light to early, some were not turning of wipers when it was not raining any more and so on. I found the one on that works correctly with my windshield (it has no graphic symbol at all).