Headlight level switch adjustment
May-30th-2008 | 05:40 PM
#1
Thread Starter
Registered User
Joined: Mar 2007
Posts: 913
From: Newark,ny
Headlight level switch adjustment
Hello group, figure I should write up the project I just did on my 2007 M3 GT to fix the horrible stock headlight level switch (used on the HID xenon system only). The owners manual says about which setting (0,1,2,3) to set the switch depending on how many people and stuff you have in the car. Though i've noticed that the adjustments seem to go way too far even from 0-1 to be at all useful for a minimal trim to keep your lights on the road. Anyhow, below is information about how to change the level adjustments to suit your needs.
Background info: The stock system has 5 resistors running from the headlight power to ground. These 5 resistors are in series and result in 4 nodes that connect to an output pin - which goes to the headlight adjustment module to tilt the headlights.
Stock values: Resistor values for the stock system are as follows: Battery connected to 715 ohms - 715 ohms - 261 ohms - 604 ohms - 715 ohms - ground. Since the voltage is off battery i'm going to reference percentages of battery voltage instead of a set voltage level. The stock percentages of batt for each position are as follows: 0 = 76%, 1 = 53%, 2 = 44%, 3 = 24%
I didn't measure the stock positions but see below for what angles equate to what percentage value.
Testing: Using a pot, I adjusted the percentage from a max of 78% down to 22% and here are the angles of adjustment for the headlights: 78% = +.161 deg from stock, 65.7% = -.622 deg from stock, 48.9% = -1.4 deg from stock, 33.5% = -2.19 deg from stock, 22% = -2.97 deg from stock. These angles were measured pulling up 16' from a wall and measuring twice every 5.25" (fence board width - cause I didn't have help).
What I figured out is that at setting 3 at stock you have about a 3 degree drop, well this equates to about 7" drop at the rear of the car - which is completely insane for load leveling since the bump stops hit at like 4.75" or so.
So I figure if each number on the dial equalled 1" of drop a the rear wheels, that would be a realistic load to see in the car - or at least close. For each 1" drop at the rear I figured 0.434 degrees of compensation is needed at the lights... so the below valuse reflect that.
Final values: From above I figured that the percentage range from 78% battery to 22% battery was a total of 3.13 degrees tilt. So to get a tilt of 0.434 degrees I need a 7.7645% voltage drop. I still need to start at the stock location so I don't have to manually adjust the level again, and here are the new values I found using stock 1% resistors - the values are measured so may not be directly available
Headlight battery - 735 ohms - 243 ohms - 243 ohms - 244 ohms - 1646 ohms - ground. The 1% values listed on the packages were 735, 243 and 1620.
This results in final percentage values are 76.37%, 68.56%, 60.75%, 52.9% - which should be the 7.76% per step and also 0.434 degrees drop per step.
So hopefully this is enough information to rebuild your headlight switch with a few resistors that most people don't have access to - but oh well, if someone wants to do the project you can get single parts through digikey or other online electronics supplier. Before closing the project I also put a coating on the resistors to keep them from vibrating or anything, if you end up with parts hanging around on the board i'd suggest using something to seal things in place after it's tested.
Good luck and ask away with any questions since you may be able to tell i'm not the best at organizing thoughts so it may be confusing.
Background info: The stock system has 5 resistors running from the headlight power to ground. These 5 resistors are in series and result in 4 nodes that connect to an output pin - which goes to the headlight adjustment module to tilt the headlights.
Stock values: Resistor values for the stock system are as follows: Battery connected to 715 ohms - 715 ohms - 261 ohms - 604 ohms - 715 ohms - ground. Since the voltage is off battery i'm going to reference percentages of battery voltage instead of a set voltage level. The stock percentages of batt for each position are as follows: 0 = 76%, 1 = 53%, 2 = 44%, 3 = 24%
I didn't measure the stock positions but see below for what angles equate to what percentage value.
Testing: Using a pot, I adjusted the percentage from a max of 78% down to 22% and here are the angles of adjustment for the headlights: 78% = +.161 deg from stock, 65.7% = -.622 deg from stock, 48.9% = -1.4 deg from stock, 33.5% = -2.19 deg from stock, 22% = -2.97 deg from stock. These angles were measured pulling up 16' from a wall and measuring twice every 5.25" (fence board width - cause I didn't have help).
What I figured out is that at setting 3 at stock you have about a 3 degree drop, well this equates to about 7" drop at the rear of the car - which is completely insane for load leveling since the bump stops hit at like 4.75" or so.
So I figure if each number on the dial equalled 1" of drop a the rear wheels, that would be a realistic load to see in the car - or at least close. For each 1" drop at the rear I figured 0.434 degrees of compensation is needed at the lights... so the below valuse reflect that.
Final values: From above I figured that the percentage range from 78% battery to 22% battery was a total of 3.13 degrees tilt. So to get a tilt of 0.434 degrees I need a 7.7645% voltage drop. I still need to start at the stock location so I don't have to manually adjust the level again, and here are the new values I found using stock 1% resistors - the values are measured so may not be directly available
Headlight battery - 735 ohms - 243 ohms - 243 ohms - 244 ohms - 1646 ohms - ground. The 1% values listed on the packages were 735, 243 and 1620.
This results in final percentage values are 76.37%, 68.56%, 60.75%, 52.9% - which should be the 7.76% per step and also 0.434 degrees drop per step.
So hopefully this is enough information to rebuild your headlight switch with a few resistors that most people don't have access to - but oh well, if someone wants to do the project you can get single parts through digikey or other online electronics supplier. Before closing the project I also put a coating on the resistors to keep them from vibrating or anything, if you end up with parts hanging around on the board i'd suggest using something to seal things in place after it's tested.
Good luck and ask away with any questions since you may be able to tell i'm not the best at organizing thoughts so it may be confusing.
December-1st-2008 | 07:44 AM
#3
Registered User
Joined: Dec 2008
Posts: 1
From: hawaii
Headlight level switch adjustment
hi..
Hello group, figure I should write up the project I just did on my 2007 M3 GT to fix the horrible stock headlight level switch (used on the HID xenon system only). The owners manual says about which setting (0,1,2,3) to set the switch depending on how many people and stuff you have in the car. Though i've noticed that the adjustments seem to go way too far even from 0-1 to be at all useful for a minimal trim to keep your lights on the road. Anyhow, below is information about how to change the level adjustments to suit your needs.
Hello group, figure I should write up the project I just did on my 2007 M3 GT to fix the horrible stock headlight level switch (used on the HID xenon system only). The owners manual says about which setting (0,1,2,3) to set the switch depending on how many people and stuff you have in the car. Though i've noticed that the adjustments seem to go way too far even from 0-1 to be at all useful for a minimal trim to keep your lights on the road. Anyhow, below is information about how to change the level adjustments to suit your needs.
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adjust, adjusters, adjustment, gt, headlamp, headlight, headlights, level, leveling, mazda, mazda3, mazdaspeed, rebuild, subwoofer, switch
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