One headlight flickers at start but doesn't come on...

Hi all, Sorry for yet another "headlight not working" post. Hopefully the symptoms are sufficient for someone to pinpoint the issue. 1) Only left low beam headlight has this issue. Right one works fine. 2) From cold start, the left headlight flickers once but doesn't stay on. 3) I turn the switch off and on a couple of times and same thing happens. 4) I leave the headlight switch on and drive for a few minutes 5) I turn off and on the headlight switch and then the left headlight comes on, *slowly* (over about 5-7 seconds). It's almost like something in the system needs to build up a charge with the headlight switch turned on for a few minutes to fully ignite the bulb. This is reproducible, every day. Any ideas? I searched the forum and I've cleaned the harness connectors, changed the switch, bulbs and ballasts (albeit with used ones) but can't seem to find the problem. Thanks all! Enlai

Oh yeah, I switched left and right ballasts between headlights and the same thing happens.

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What's "same thing"? Did the problem follow the ballast? If so, you probably found your answer. Did you swap bulbs too?

I had the same problem where one headlight was not lighting. I removed the offending head light. Looked inside the plug. I saw a contact pin slightly bent over. I stood the pin up erect with long nose pliers. I broke off the plug holder from the plastic so I could hold the plug while inserting the headlight back in place. Problem solved. I think replacing these headlights exactly into the plug can be a hit and miss job. The plug needs to be held solidly in place and enough force on the headlight to make good contact. I suggest that yours is not making a good contact. BTW I removed my other headlight and snapped the the plug (on purpose) away so I could hold it and push it cleanly onto the head light when putting it back in place. I don't see any need for the plug to be in a fixed position. Mine has held strong for the past 2 years and I don't expect it do anything else only hold where it was put forcibly in place.

+1 on the loose headlight contact... One day I saw my right headlight stick-out more than normal, not flushed anymore, so I knew that headlight somehow popped-out loose on its own. So I used the special tool to release the latch and carefully push it back-in and everything was fine again. So you have to make sure that you have good contact upon installing those headlights into their sockets. They need to snap-in nicely. Cheers,

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Also, when using the special wrench to install make sure you get a loud snap to indicate that the headlamps are locked into place. Sounds like whoever removed the lights previously didn't do that. I don't think the lights will move if they are locked into position.

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This question needs to be answered before any further guesses can be made... Other members have posted up images showing the insulation being totally cracked and degraded for the headlight wiring - you might have a short/ground. HID ballasts generate a lot of voltage at startup; the ignition pulse can be up to 25K volts. A wiring fault between the ballast and the bulb could be the issue.

Sorry for the ambiguous statement! "Same thing happens" means the left (driver's side) headlight still exhibits this behavior even after I swap ballasts between left and right headlights.

Since you've exculpated the ballast, it must the the bulb, the switch, or the wiring. If you have some MAF or contact cleaner, try hitting the headlight switch body with it. It's a long shot, but maybe a dirty contact point is to blame.

Thanks. I replaced the switch with a brand new one... didn't help. I don't think the bulb is the issue as it lights up. I swapped the left bulb with the right one and the driver side still has the problem. I used MAF at the contacts of the harness, used a diamond file to clean the contacts on both male and female harnesses, etc so I don't think it's the contacts in the harness. I have a feeling it's something that is isolated to the left side... perhaps the wiring. My car is a 2002 996 so it's 14 years old. Have you guys heard about wiring aging to a point where there is built up resistance and hence lower current flowing?

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Have you tried just driving with one head light? I mean... come on try a little, nothing is forever and there's got to be something better than in the middle. Just a thought

Lol. Fortunately, I just have to leave the headlights on for a few minutes (the right one works) and then turn the switch off and on again, and the left light will light up gradually (over about 5-7 seconds).

I have the same issue in my '03 c4 cab. I have not gotten around to troubleshooting it yet.