Xenon Lights Range

[tonedef]

Since I bought my S3 I have been having trouble with the headlight range like many other people I guess. Now winter is coming I'm getting more serious about fixing it and have tried new level sensors front and rear with little success.

I just downloaded VAG COM 409.1 and bought a serial cable, I can read the voltages from the level sensors, approx 1.4 volts front, 2.8 volts rear with the car sat on level ground. Are these something like right and if so is there anything else I can do to the lights with VAG COM?

Cheers,
Tony

 

[Sebastian]

Got the part number of the level control module?

 

[tonedef]

Sebastian, The level sensors are both p/n 4B0 907 503 is what you were asking for? My wife is out in the car right now, I'll plug in VAG COM when she gets home and read off any other numbers.

Cheers,
Tony

 

[Sebastian]

Not what I asked for but I found it anyway.

The specification for the sensors is 1.56...3.45 V, so the front sensor is out of range. FWIW, a current version of VAG-COM would have shown these values.

 

[tonedef]

Thanks for that Sebastian, I did find later that the p/n of the controller is 4B0 907 357. I'll have another go at making it work later today, on a drive the front often drops to 1.1/1.2 volts.

And next job is updating VAG COM for the help.

 

[Uwe@Ross-Tech]

Is your car lowered? I.e. different springs? If so, you're going to need to (mechanically) adjust that sensor to get the voltage up.

If the car is stock, the sensor shouldn't read that low.

-Uwe-

 

[tonedef]

Hi Uwe,

No, the car is running standard ride height, I considered that too. Since last posting I started considering the mechanical arrangement and have done the following:

1) As the headlight range was low, the controller must be seeing that either the front of the car is high or the rear is low.

2) When the front of the car rises, the arm of the sensor falls, therefore moving the arm up will raise the headlights.

3) The front sensor to suspension arm link rod has a bend in it therefore by partly straightening this bend the headlight aim can be raised.

By doing the above I now have a higher aim on the headlights, however the front sensor is reading below 1 volt, (further out of range than before). If I now jack up the front or rear of the car the lights adjust to compensate to the same level (I have the beam pattern drawn on the inside of my garage door to check against after every journey!).

Maybe the reading from the rear is incorrect although I do not understand how that could be as all the brackets appear standard, the sensor is new and the link rod is straight. The only possibility is if a previous owner fitted a new (incorrect) link rod but I cannot believe that has happened.

It remains a mystery although I can now see to drive in the dark!

Cheers,
Tony