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Flickering right headlight

4241 Views 10 Replies 3 Participants Last post by  HerbP
I have an early 2005 645Ci. I apologize for the length of this but there's a lot going on. I recently cured an AHL issue by replacing the AHL module behind the glove box (thanks HerbP) The right (passenger) side headlight had been flickering prior to this repair and I had hopes this repair would fix both problems. It didn't. So currently the right side low beam flickers intermittently and occasionally flashes like a camera flash. I ran the diagnostics (ISTA-D) with nothing showing up. Lights activate when they should and they move around as commanded. Also the headlights don't seem as bright as I think they used to be. Xenon bulbs are a little too expensive to just start replacing and I'm a little confused about the "ballast" and "igniter" comments I've seen through my searches of the forum. So I'm looking for some guidance. Everything on this car is stock and I've confirmed moisture and corrosion are not issues here.
I thought I'd mention I found while running the diags. Under normal driving my low beams and high beams come from the same bulbs. The xenon shutter changes to switch from low to high beam. If I pull back on the beam changer lever to "flash" the lights at someone, the other set if bulbs light up. When running the diag software testing the high beams, it lights up the same set of bulbs as the "flash" bulbs. So that also has me scratching my head.
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You could possibly have a bad connection, or the bulb is on the way out.
Is that how a bulb would typically wear out? I have my doubts about a bad connection since I've already had everything taken apart troubleshooting the AHL issue. The flickering symptom was there before the AHL stopped working and I thought the two problems were related but the AHL module only fixed that part of it. I'm going to try new bulbs and will report back. Thanks for the advise.
If the bulb was on it's way out it could flicker or change color. Another issue could be the ballast on the light itself.
Is that how a bulb would typically wear out? I have my doubts about a bad connection since I've already had everything taken apart troubleshooting the AHL issue. The flickering symptom was there before the AHL stopped working and I thought the two problems were related but the AHL module only fixed that part of it. I'm going to try new bulbs and will report back. Thanks for the advise.
Thanks again for the input. I'm a little confused about the ballast. That is not the same thing as the igniter, correct? Where is the ballast located? When I drove to work this morning the outside temp was about 15 degrees F and for the first 15 minutes of the ride the right headlight was constantly flickering with and occasional super bright flash. Only the right side. Probably flashed about 4 or 5 times. Makes me think it probably is not the bulb.
The ballast is considered the bottom module, & the ballast igniter is the part that fires the bulb. What kind of codes are you getting on a cold morning, verses the warmer part of the day?
Thanks again for the input. I'm a little confused about the ballast. That is not the same thing as the igniter, correct? Where is the ballast located? When I drove to work this morning the outside temp was about 15 degrees F and for the first 15 minutes of the ride the right headlight was constantly flickering with and occasional super bright flash. Only the right side. Probably flashed about 4 or 5 times. Makes me think it probably is not the bulb.
Sorry meant to say igniter. I believe there is no ballast in these bulbs.
The ballast is considered the bottom module, & the ballast igniter is the part that fires the bulb. What kind of codes are you getting on a cold morning, verses the warmer part of the day?
No codes, just more of the bright flashes than in warmer temps. Maybe just a coincidence. And to think I just had the bumper off last month troubleshooting the AHL module. For what it's worth, the side and bottom modules on both sides looked pristine. No moisture, no corrosion. I guess they can fail without getting wet. It'll have to wait til the weekend. I'm going to swap the left and right modules and see if it tracks. More to come.
If you run the diagnostics on the modules, are you getting any ecu communication problems? If you can communicate with the modules & they work as they should, you might have igniter problems. I am not sure if you can run diagnostics on the igniter? I would hate for you to pull the bumper again for no reason.
So, short story. I think I have cured the issue of the flickering/flashing headlight. BULB! I had already run some diagnostics which I'm fairly confident communicated with both modules mounted in the headlights. FWIW, it's pretty cool running the AHL test and watching the lights move all over the place. So, in concurrence with HerbP's comments I decided to first check out the igniters. I swapped the left and right and the symptom did not follow the igniter. My new bulbs had arrived Saturday from Pelican Parts so I next installed them. Success! Thanks for all the advise boys. Looks like I'm all fixed up.
Glad you got the problem resolved. The only way too learn the software is playing around with it, glad you learned something in the software for future reference. It is sometimes confusing to use, since it was written by German engineers.
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