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Passenger Headlamp Question/Issue

Discuss problems you have had or are having with your Z4
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Erikh425
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Passenger Headlamp Question/Issue

Post by Erikh425 » Sun Jun 13, 2021 3:08 pm

Hello all,

I have been on this forum for awhile, but I think this is probably my first post. I have always loved the look and the feel of the Z4's, and I always have to have something in my garage to tinker with. So, when a local gentleman wanted to trade his Z4 for a Jeep I had refurbished, I decided to take the plunge. For the better part of the last 25 years I have tinkered with all types of cars, from American muscle cars, rat rods, Japanese tuners, rebuilt some motorcycles and now I have this BMW. It is the first BMW I have owned, and I really like to drive it. It is a 2005 Z4 2.5 with about 105K for miles. I've owned it for about 3 months, and I live in the US in SE Georgia. It lives in my garage, rarely goes out in the rain and has only been hand washed since I have owned it. It also just dawned on me, I don't have a good pic of it (I'll work on that) It has needed some minor cosmetic work, like broken cupholders, the notorious cracked 3rd brake light, and some other small stuff.

I am stumped by a headlight issue I am having. Here goes. The lamp out illuminator on the dash has come on once in a while since I got the car. When it came on, I would get out and walk around the car, but all of the bulbs seemed to be working properly. Recently the lamp out illuminator came on and the passenger side low beam headlamp is out. It is a halogen H7 bulb. I pulled the bulb and checked it for continuity with an ohm meter, and the bulb shows good. I also replaced the bulb with a new one, and it still doesn't work. I used a multimeter to see if there was power to the bulb, and there is no power at the plug. I have traced the wires as far as I can by pulling back trim and it all looks good. I can't imagine it is a fuse, because it seems there would be other things not functioning.

I have searched this forum and the WWW and have found most of the posts relate to Xenon headlights with a ballast and an igniter. To my knowledge, there is no ballast or igniter with a halogen bulb (but, it's a BMW, so I could be wrong). I am thinking maybe there is an issue with the light control unit. I believe that is part of the light switch and the vehicle pre-check on start up is also integrated into it. I'm not sure I am going to mess with that yet. My other option is to remove the wheel, some trim and maybe the front bumper to better trace the wires. I assume they will go into a loom at some point and I will lose them.

Question I have. Does this car sense a drop in voltage/continuity and throw the error code on the dash? and when there is an error code for the light on the dash, does it cut power to that circuit for safety or something? I have tried to clear the error with a Scanguage II that I have, but it won't read the headlamp error. I was also thinking of disconnecting the battery for a period of time to see if it would clear the error and maybe restore power to the circuit, but I am not even sure that is a thing.

That is where I am at. Sorry for the long post, but I wanted to be thorough and figured I should work an introduction into it :)

Erik

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Chippie
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Passenger Headlamp Question/Issue

Post by Chippie » Sun Jun 13, 2021 5:22 pm

Hi and welcome to the forum
Here’s a link to a post with the fuse numbers and locations
viewtopic.php?t=38888

It may be worth while checking they are all ok and not corroded
Can’t really help any moron afraid
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Erikh425
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Passenger Headlamp Question/Issue

Post by Erikh425 » Sun Jun 13, 2021 5:33 pm

Thanks for the welcome and the link. I will check the fuses before I go taking off body panels or removing the LCU.

Erik

Erikh425
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Passenger Headlamp Question/Issue

Post by Erikh425 » Sun Jun 13, 2021 5:53 pm

I see this got changed to the E85 problems section. Thanks to whomever did that. I could not get it to post here originally for some reason.

Erik

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Zulu4
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Passenger Headlamp Question/Issue

Post by Zulu4 » Sun Jun 13, 2021 7:12 pm

The car does check for current flow through the bulb at start up (cold monitoring) and when in use (hot monitoring). I do not think it will cut power to the circuit if a bulb blows (but I may be wrong).
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Erikh425
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Passenger Headlamp Question/Issue

Post by Erikh425 » Sun Jun 13, 2021 11:15 pm

I believe I got it figured out, so I will post what I did in the event others need it at some point.

I checked all of the fuses and they were good. I then decided to trace the wires as far as I could. I got the inner fender liner off far enough to look behind. I traced the blue and black wire from the H7 low beam bulb to a square connector where all of the headlight wires connect. This connector looks like it should be mounted on the inner wheel well, but it was hanging loose. So, I wiggled it and then started the car and turned on the headlights. Low and behold, the passenger light worked like it should. I wiggled the connector a little bit and the bulb went out. So, I am assuming this is my issue.

I am planning to take the wheel and the inner fender liner off in the near future so I can mount that connector correctly. I also plan to take the connector apart, clean the connections and put it back together. I might even throw some dielectric grease on it, but I am not sure that is the right thing to do, I'll research that.

I will take some pics on my phone and try to attach them here. I am not sure I have enough posts to post pics, but I will try.

Thanks to those who chimed in and to those who read my first post. I will try to be less of a lurker here in the future.

Erik

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