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Bloody hell!

As I said yesterday, I washed my car. Afterwards I did the lights and levels to make sure that everything was tickety-boo.

It wasn't. Front left headlight didn't work on the normal (non-high) setting. It has been doing this, but intermittently. Sometimes turning the headlight off and back on would 'fix' it (high beam always worked fine).
But not today.

I didn't feel like going to Cyril and saying "please, seriously, change the damn headlights". I guess he was doing me a favour by just clipping it back in place, but there was a specific reason why I wanted the bulb changed.

That reason was partly because the bulbs were coming on two years, so they've seen some use. Partly because it's a massive pain in the arse to get to the bulb. And partly diagnostics of whatever is acting up.

You see, it could be a faulty control stick, it could be the wiring harness, it could be the bulb..... but honestly the simplest thing to deal with is the bulb, so start there.

I didn't want to drive around with only one headlight, so I reached under to see if I could undo the socket from the bulb. The little wire harness popped open (lovely).
Now, I should put some context here. I was not only working blind, but had to put the steering on full lock and reach under from where the wheel would normally be.

I noticed the bulb wobbling in ways it shouldn't (the central part had come away from the positioning ring flange thing), so really there wasn't much choice but to try to get the thing out.

After a lot of fiddling, aided by the flange being able to rotate, I managed to ease it around the retaining clip. Normally the clip only goes down when the socket/wiring is out of the way, but the thing wouldn't come apart so I had to fiddle. A lot.

I managed to bring the busted headlight assembly down to the tyre, but no further, the cables weren't long enough. But it was down far enough that I could wedge a screwdriver in to start to try to get the sodding socket off the bulb.
It was in danger of breaking the socket, but eventually the bulb's contact broke and the thing came apart.

I popped a new bulb into the socket and... it worked.

I put the new bulb in place and fiddled for ages, but the thing was simply not going to latch into place.

Bulb fitting
Bulb fitting.

I've given up on it for today, the big rubber boot more or less holds it in the right place. I might have a try some other day, but I was seriously in danger of "fixing" it using the pickaxe.

Everything all hooked back in place... the headlight didn't work.

So I took the socket off and put it back on again. It worked now.

Here's why.

Corroded contact
Corroded contact.

The contact looks burnt. I'm suspecting that the connection was not good (dirty?), and this created resistance that was dissipated as excess heat where excess heat shouldn't be.

Of course, the connection is still not good but for now it works. I'm not sure it's really possible to clean up the contact, especially if it looks anything like the bulb terminal. I may have to purchase a replacement H4 connector and find some way of replacing the one that is currently fitted. Well, that ought to be fun.

It's worth noting that this car uses the older design of headlight. There is a rubber boot that goes between the bulb body and the plastic shroud around the headlight fitting (you can see this above), and the socket plugs in afterwards. The socket has no protection, so all the crap thrown up from the wheel is splattered onto the back of the socket, and ultimately into the contacts.
I think the newer headlight assembly has a screw-on cover that protects everything. A much better idea.


Well, my shoulder hurts. My arm hurts. And, of course, my fingers hurt. So I think if I'm ever buying a car in the future, my main question should be "Can I change the bulbs without dismantling parts of the car or performing improbable gymnastics?". If the answer is not yes, okay, look at a different car...



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Gavin Wraith, 20th February 2023, 22:48
My last and most expensive car, bought second hand in 1999, was a Honda Accord Coupe. It was excellent in every respect, except for changing the headlamp bulbs. As in your photo, there was a spring latch and a rubber boot, but getting at them seemed impossible for human anatomy. However the last time they were changed was at Frederikshavn in northern Jutland. After seeing my youngest daughter off on a train, ultimately to Paris, I consulted a local telephone book and found a Honda agency in the industri omraad there. There they sat me down with a cup of coffee and did the job in fifteen minutes; no charge for coffee or labour, just the bulb, which was not expensive. The experience added to the pleasure of that holiday.
Rob, 20th February 2023, 23:27
Part of the reason for complicated and ridiculously tight fixings holding a bulb in place is to make sure it's in exactly the right spot within the reflector. Move a bulb just a little away from its designated position, and the shape of the beam it casts will be wrong. Same goes for fitting the wrong bulb. It might fit, and light up, but the filament could well be in the wrong place..!
Rick, 21st February 2023, 20:32
Stopped by the local garage today. The mechanic had a look, discovered that part of the mechanism is bent out of shape (actually, you can see that in the photo, lower left) and fiddled with it until the bulb finally stayed in place. 
Didn't want payment for ten minutes of fiddling, so I left the receptionist €10 for "pour boire" (to get himself a drink). 
My arm hurt quite a lot today from being wedged between the wheel and the wing panel. So I wasn't about to fart around with it again. 
He said to do a proper repair, I'll need to take the headlamp assembly out, or at the very least take the wheel off so I can get under and see what I'm doing. 
Uh... His "fix" will have to do for now. ;) 
It took several tries to get the plug in the right place for the headlight to come on at all. So, yeah, the socket side is probably as corroded as the lamp prong. 
The mechanic suggested a screwdriver and emery cloth to shine it up, but I've taken the Plan B option. I've ordered a replacement H4 socket and some heat shrink wire cover from Amazon. The plan is to clip off the old socket and solder a new one in it's place. Given its proximity to the wheel, I'm not keen on using screw terminal blocks or anything like that. 
Hmm, not sure quite how to shrink the plastic cover - wave a lighter under it? Any ideas? 
Rick, 21st February 2023, 20:48
Oh, and he said that "Just reach under the wheel and fiddle? Easy!". 
Some other cars require dismantling to change bulbs. 
Rick, 21st February 2023, 20:58
Turns out, this was getting a bit out of control, so in the EU Regulation #48 (2016/1723 (L265/149)), it says: 
5.23. Lamps approved with light source(s) according to Regulation No 37, except when such light sources are used as non-replaceable light source(s) as defined in paragraph of this Regulation, shall be fitted in a vehicle in such a way that the light source can be correctly replaced without the need for expert assistance and without the need for special tools, other than those provided with the vehicle by the manufacturer. The vehicle manufacturer shall provide with the vehicle a detailed description of the procedure for replacement. 
Rob, 23rd February 2023, 03:36
Heat shrink... Lighters work but you've got to be careful not to burn things. If be warey around a car. I use a hot air blower on my cheap Chinese soldering station, but a hair dryer on max or hot air paint striper might be just as good.
Anon, 24th February 2023, 18:55
Ah yes, the joys of replacing bulbs in modern cars. My Audi pre-dates that EU regulation. Replacing the passenger side bulb (this is on a RHD UK model) is easy enough. Replacing the driver side? Prepare to dismantle half the air intake assembly to gain access to the back of the headlight housing. 
Slightly easier on the current (2007) model as it uses reflectors for the dipped beam, the previous one (2003 model) used projector dipped beams. Which means it's even harder to get the bulb in when you've got limited access. It uses a pair of H7 bulbs, one each side for dipped and full beam. 
I would say "sod it" and fit LED bulbs, HOWEVER... if I do that, the CAN-BUS system will detect it as a bulb failure. There are work-arounds, which involve either putting a ballast resistor across the bulb to 'fool' the system into thinking it has a standard halogen bulb, or using the headlight output to drive a relay coil (which should have a low enough resistance not to trip the CAN-BUS) then use the relay contact to apply power to the LED bulb. 
To put this into perspective, a set of two Osram Nightbreaker H7 (ultra-bright) bulbs goes for about £30. A set of Osram (or was it Philips?) 'LED Driving' bulbs goes for about £100 - plus another £50 for the CAN-BUS control interface. And you'll need two sets, one for full-beam and one for dipped. 
The irony of course is that if your car was built before around 2001 (when they started fitting the lamp failure detection) you can just pop a set of LED bulbs in for about £20 or so. And post-2016 (eg the new B9-series A4) apparently has a switch accessible by the OBD port to disable the 'lamp test' function and allow retrofitting LED bulbs. But if your car was made between 2001 and 2015 - you're screwed if you want to upgrade to LED lighting!
Rick, 26th February 2023, 14:07
I'm not going to fix the headlight this weekend. Sunny, but a freezing East wind. Just no. 
As for LED headlights, they aren't legal here (unless within *very* specific parameters, such as the ones in the Citroën Ami) because they're generally TOO bright, it's dangerous to oncoming drivers when LED dipped beam appears brighter than normal main beams. 

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