Headlight Flicker
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Junior Member
Joined: Feb 2014
Posts: 18
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From: Canada
2012 E350 4matic Coupe
Headlight Flicker
Headlights have been flickering on and off intermittently for the past month. Car has factory bi-xenons with Osram Xenarc bulbs.
Passenger side started flickering, sometimes turns off for a few seconds and turns back on. Some days it won't flicker at all. Happens when driving or idling.
Swapped the bulbs, and the driver side started doing the same so I got new bulbs. Everything was good for a few days and then the driver side started to flicker again. Swapped bulbs around again and the flickering followed to the passenger side.
Wondering if it has anything to do with the alternator or battery. Car was bought used from Land Rover, battery was dead and they replaced it with a Land Rover battery, not AGM. Battery died 6 months ago when I left my key in the ignition overnight. Boosted it and haven't had problems since.
Looking at the vehicle data display, the UB battery voltage is 11.9v before starting and goes to 14.2v shortly after starting. Voltage drops to 13.4 when accelerating and goes back to around 14.0. IB shows 15-20a after starting and slowly drops to 0.5-1 after 15 minutes of driving.
Is this just bad luck with bulbs or is there something else going on?
Passenger side started flickering, sometimes turns off for a few seconds and turns back on. Some days it won't flicker at all. Happens when driving or idling.
Swapped the bulbs, and the driver side started doing the same so I got new bulbs. Everything was good for a few days and then the driver side started to flicker again. Swapped bulbs around again and the flickering followed to the passenger side.
Wondering if it has anything to do with the alternator or battery. Car was bought used from Land Rover, battery was dead and they replaced it with a Land Rover battery, not AGM. Battery died 6 months ago when I left my key in the ignition overnight. Boosted it and haven't had problems since.
Looking at the vehicle data display, the UB battery voltage is 11.9v before starting and goes to 14.2v shortly after starting. Voltage drops to 13.4 when accelerating and goes back to around 14.0. IB shows 15-20a after starting and slowly drops to 0.5-1 after 15 minutes of driving.
Is this just bad luck with bulbs or is there something else going on?
Last edited by wvien; Jan 23, 2017 at 12:56 PM. Reason: More info
Thread Starter
Junior Member
Joined: Feb 2014
Posts: 18
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From: Canada
2012 E350 4matic Coupe
I had the battery checked at Napa over the weekend and they said it was good. Hooked it up to a charger and left it overnight.
New bulbs are Morimoto XB from theretrofitsource. I swapped in the working Osram bulb to see if I still get flickers, haven't seen anything in 2 days. Will try swapping the bulb again to see if it comes back.
New bulbs are Morimoto XB from theretrofitsource. I swapped in the working Osram bulb to see if I still get flickers, haven't seen anything in 2 days. Will try swapping the bulb again to see if it comes back.
Thread Starter
Junior Member
Joined: Feb 2014
Posts: 18
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From: Canada
2012 E350 4matic Coupe
Last night I had one Morimoto bulb and one Osram bulb in. Both of these bulbs have not flickered before.
The new Morimoto bulb started flickering and then shut off for a few seconds before turning back on. Voltage was showing 13.4 at the time, car sitting in the garage idling.
The new Morimoto bulb started flickering and then shut off for a few seconds before turning back on. Voltage was showing 13.4 at the time, car sitting in the garage idling.
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Joined: May 2016
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From: Perkasie, PA
2014 C300 Sport
Morimoto does usually make quality products, but for me at least it's been hit or miss with their bulbs. I've had bulbs last years, and others last just months.
The voltage does seem low though as well. I'd rule out the ballasts as it seems to be happening on both sides.
The voltage does seem low though as well. I'd rule out the ballasts as it seems to be happening on both sides.
Thread Starter
Junior Member
Joined: Feb 2014
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From: Canada
2012 E350 4matic Coupe
Did a little googling and it seems like the BMW guys are having headlight flickering problems as well. They think the problem is faulty grounding at the tail lights. I took a look at my passenger side tail light harness and the ground pin had some brown stuff on it. I just had the car in for the tail light recall but looking at the invoice they only replaced the lamp carrier and not the harness. I soldered on a ground wire to the plate on the carrier for now. Will have to take it back to the dealer to deal with the harness. Didn't notice anything on the passenger side. After I soldered the ground wire on I went for a short half hour drive and didn't see any flickering. Will see how it goes for the next few days.
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Joined: Jan 2016
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From: Ottawa, ON
2012 C350 4Matic Sport
Did a little googling and it seems like the BMW guys are having headlight flickering problems as well. They think the problem is faulty grounding at the tail lights. I took a look at my passenger side tail light harness and the ground pin had some brown stuff on it. I just had the car in for the tail light recall but looking at the invoice they only replaced the lamp carrier and not the harness. I soldered on a ground wire to the plate on the carrier for now. Will have to take it back to the dealer to deal with the harness. Didn't notice anything on the passenger side. After I soldered the ground wire on I went for a short half hour drive and didn't see any flickering. Will see how it goes for the next few days.
Sorry for the slightly off topic story, but, I can easily see how an even slightly bad ground at your tail light could cause electrical abnormalities at the headlights.
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Thread Starter
Junior Member
Joined: Feb 2014
Posts: 18
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From: Canada
2012 E350 4matic Coupe
So grounding the tail lights didn't solve the problem. Dropped by an alternator shop yesterday and they said voltage dropped to 12.7 a few times under load. Going to rip out the alternator tomorrow and replace.
Junior Member
Joined: Jan 2016
Posts: 47
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From: Ottawa, ON
2012 C350 4Matic Sport
Ughh... that sucks, but, hey, you did some good troubleshooting and it sounds like the alternator shop found the root cause anyway..
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From: Canada
2012 E350 4matic Coupe
Pulled the alternator, took it to 2 different shops to test and it tested ok. There was a very slight noise coming from the bearing. No one in the city had a voltage regulator in stock. Decided to put in a remanufactured alternator since it's already out of the car and the bearing noise. $400 later and it's still flickering.
Any other ideas?
Any other ideas?
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2012 E350 4matic Coupe
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2012 E350 4matic Coupe
