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Discussion Starter · #1 ·
Applying to us European 300c's who dont have automatic headlights and want that feature. This was installed already on the car but 'deactivated' by a small plastic tab that we will remove, allowing the switch to be turned back from position ' 0 ' .
Note this could work on models up to 2008 (pre facelift) I am not sure if this will work on facelift models.

Tools needed:
Small/medium flat blade screwdriver
Electronic side cutters/old flat blade screwdriver
A cooker/blowtorch for heating old flat blade screwdriver (you'll get the idea)
2 rags for testing.

This can be done with the switch assembly in the car or removed. I had bulbs to replace so mine was done after removing the assembly from the car and retrieving 2 out of the 3 clips that sprung into the crevasse behind it!

Headlight switch-

First up is removal of the knob. Look up under the switch and you can see there is a small indentation to where you can stick your flat bladed driver.

Carefully insert the 'driver in and prise up gently removing the knob, You might want to shield the bezel you are using as lever, I didn't.

Once the knob is off, You are left with this, And we can use this to test if the feature is enabled in your car.

If its been removed from your car, plug it back in, and using your fingers turn the switch counter clockwise. It should click back.
If you are performing this mod at night, Turn on the ignition and start the car. Your lights should turn on, If it works, Great! We can modify the switch.
If you are doing this in the day, We need to fool the car to turn on the lights, so grab 2 rags.
Put one rag on the dashboard light sensor this is what the EVIC uses to measure the light:

and then go outside and put one on the rain sensor:

Turn on the ignition and start the car. The lights should light up. If they do, Great, Modify the switch!
I will cover the 'setting up' of this later.

Now either remove the switch or leave it in situ.
There is a little tab, at the 3 o clock position seen in the picture of the removed knob. Its that tab we will be removing.
Either start going at it with a set of electronic side cutters or like I did? Used a hot screwdriver warmed up on the cooker to burn the plastic off, Like so:

Tidied up. You need to make sure that its removed and smooth, It doesnt have to look pretty:

Once that's done and you've made peace with the wife for stinking the kitchen out with burning plastic, Reattach the knob and push down firmly, noting the alignment beforehand. Then check operation of the switch, Switch between Off sidelights and main, back to Off, and switch it again, to the left, If it moves freely, Well done! If it doesn't, Remove the knob and tidy it up a bit more.
Leaving you with this:

Now lets set it up.
Access the hidden menu on the 'EVIC' By pressing the music note button and the compass button.
Navigate to this screen:

These are the settings we can tweak/change

TC = Threshold Counter. The length of time that the set threshold value (THLD) is applied, so that the light is switched on or off.
The higher the value, the longer it takes for the light in the dark turned on or off in the light.
Thld = (Threshold) Set Daylight. (You can select between 150 to 220)
The smaller the value, the earlier in the day, the lights turn on.
This goes from <100 (extremely light / sun) to> 220 (dark).
So the smaller the value, the BRIGHTER it is outside.
This is 150 - 220 adjustable.
150: lights switch on in the light (Dawn)
220: lights on in the dark (dark)
Mine is set to 180.

Hope this helps.

Credit goes to German 300c forum in the meantime for helping me do this mod, and for the pictures of the Lightsensor and EVIC.
If there is an issue of using their pictures, Please contact me and I will remove them. I will get my own pictures hosted up soon and will amend them.

19 Posts
Hi monkeh

Excellent write up i now have auto headlights,thanks for that. But i cant seem to find the setup on the evic, i can get the screens up just not the one you show. Any Ideas

28 Posts
I have just modified my light switch. Don't know where you guys get your info from for this sort of thing. I have got my settings at tc 70 thld 180. I was amazed at the extra info in this Easter agg menu. Once again I don't know where you guys find all this stuff but I am very glad you do
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