Hey guys! I'm gonna install an Auto Headlights kit in my 98 528i. I need to find out if my headlight switch sends a ground or 12v signal to turn on the headlights/parking lights. There are three different ways to install the switch:

1) Both park lights and low beams on by 12v
2)Park lights on by 12v/ low beams by ground
3)Park and low beam lights on by ground.

which one is for my 98 528i??

http://www.sens56.com/SenS56_Manual_ENG.pdf

If you look at the instructions I have to tap in the wiring where the switch is at but first I need to find out what signal is sent when switched on. I read somewhere that the switch sends a ground to the light module and the module sends the power. If this is the case do I set up the kit to send a ground unit?

You can see the start of my question here: http://forums.bimmerforums.com/forum/showthread.php?t=898040

Anybody??

Thats a very interesting system you found.

stick your multimeter on the wire and test it... :)

I just tried my test light and nothing. I hooked it up to a ground and 12v and none of the wires reacted!! I'm stumped!

stick your multimeter on the wire and test it... :)

take lead from test light wrap around handle...
take handle in right hand, step out in front yard.
using an overhand motion toss test light into the darkness...
then go get a multi meter


BTW
WAS tHE IGNITION... not accessory, not radio, but IGNITION fully on?
if not that is your problem.

I actually had the car started so I wouldn't run the battery down. I know it's just a test light but it should tell me something right? Even if the switch work with just a ground it would light up if I had the tester to a positive source.

test lights are notoriously imprecise tools... like measuring inches with an odometer.

so you had the switch and wires pulled out so you could test the wires as you turned the switch off and on... right?
You didn't have the switch not plugged in... right?

I'd expect if the lkm was ground switched by the switch tht there would be 12+ on the wire between them when the switch was off and it would show ground when on.

Yep. I pulled bezel out with the switch attached and everything was in working order as if it was still installed. I tested each wire by switching from parking lights to headlights and switching the test light from ground to 12v and nothing happened. Where is the LCM? Maybe I should test from there?

Found the damn thing. It's so many wires coming out of it. Been searching for the past 30 minutes for a diagram. Are there any online? Anybody know the wires that trigger the parking and headlights?

I have a voltmeter now so I'll be testing for voltage. What should I be looking for? If there's voltage which configuration so I be hooking the lights up by? Somebody suggested putting power to the wires and see if the headlights come on but that asking for trouble if you ask me.

it sends a ground

100% positive

So I just need to ground one of the wires and the lights would come on? I wonder why my test light didn't light up when I put power to the wires and turn the head lights on??

Okay. I made a chart on the voltage through the four wires. This was done with a tester set to dv 20v. Four wires to the switch: Brown/Black, Gray/red, yellow, and black.


With the tester hooked to a 12v power source and searching for a ground:
Lights -----Brn/Blk ----Gry/red ----ylw---- Blk
Off ---------14V .----------85 -------14.04 ---14.05
Parklights 13.93 --------1.45 -------13.95 ----.49
Headlights 13.90 -------1.50 --------.40 ----13.90

Next chart is with the tester hooked to a ground source and me using the red terminal:
Lights -------Brn/Blk ----Gry/red ----ylw ----Blk
Off ------------.01 ----------13.20 ------.01----- .01
Parklights ----.02 ---------12.50------ .02----- .85
Headlights--- .02 --------12.50 ------13.98 ----.02

So what is this telling me? I see that the Brown/Blk wire is always grounded and the Gray/red wire always has power. Also it seems that the Yellow wire gets power when the headlights are on and the Black wire get's power when the parklights are on.

And an added question. Does my car have relay's for the headlights? If I can find those maybe I can tap to them instead of the switch itself. Would they be in the same spot at this car?
http://forums.bimmerforums.com/forum/showthread.php?t=735753&referrerid=56200

Wish I had a manual. This is starting to suck.

yes. all the lights are controlled by the lcm. its basically a huge relay