Headlight Auto Levelling System

Lexus-IS · December 19, 2017

53 minutes ago, is200 Newbie said:

Have you tried to reset the ECU - battery lead off for half an hour or so and reconnection.... Worth a try, costs noting other than resetting windows etc

I will try that tomorrow. Just got the following information:

Very useful information, except in the instructions it says connect the + lead from the Battery to terminal 1 but in the illustration the + lead is going to terminal 3. I think their Battery illustration might be wrong LOL. Or I might be referring to normal AA batteries and this guide is referring to the smaller batteries which might be the way in that pic. Nevertheless, this seems like a very good test to test the sensor. Seeing as I have my old one off now I decided to test it and it is always reading 0.5V regardless of what degrees the sensor is at. So this leads me to believe the front sensor was faulty. Tomorrow I will just test the new second-hand sensor i put with this same test and see how that responds. I will also test the back.

WIll keep you all posted.

Lexus-IS · December 19, 2017

So by looking at this test procedure it seems to me that the AFS ECU sends 4.5V via pin 1 and 3. And the height sensor is the essentially a variable resistor that reports back either 4.5V, 2.5V or 0.5V. Using these reported voltages the AFS ECU then makes the decision how to adjust the lights. I'm wondering as a test if I should maybe turn the car on with the sensors removed and test how much voltage comes out of pins 1 and 3. If it is 4.5V as predicted, then loop pin 1 back to pin 2 essentially fooling it into reporting back as +45 degrees. And then technically it should adjust the lights right?

Lexus-IS · December 20, 2017

OK here's an update. The auto level is working now. I replaced the rod with the seized ball/knuckle joint. I figured out how it works. Basically the connector going to the sensor has 3 pins. Pins 1 and 3 are + and - from the AFS ECU. The ECU provides around 5V of power through these pins. The height sensor reduces this to about 4.5V. The height sensor is essentially a variable resistor. This allows the voltage to change from 4.5v to 0.5V. the 4.5V. The ECU then reads this to determine angle.

Anyway my height sensors are now working. And one way i tested it for sure is with the car on level ground i crawled underneath the rear sensor and loosened the bolt that lets you adjust the height. When I moved this up and down I could clearly see the lights moving.

But now I have another issue, with my car on level ground and against a wall, I can see my beam is higher than it was before because the level sensors are working. However, the right side seems much lower than the left side. Below is a illustration of how I am seeing the beam reflection. Ideally I wanted to get the right one to move up so that the lines meet. However the right was much lower and I had to adjust the cog almost all the way to the limit to get it looking like below: Question is, is there any other way to raise the right hand side? The cog I am adjusting is the one on top. I know there is another cog but I didnt think the other cog will effect vertical height. Any ideas?