Lights?

[Carrie]

Um, probably something very obvious, so I'm hoping for an easy answer. Over the last two weeks one of my rear lights has been getting progressively dimmer until it's now barely lit. Anyone any ideas why?

I have this worry that I probably shouldn't have said there was an easy answer because my car has always been tempremental where its lights are concerned. It eats rear lights for breakfast and one time managed to blow every light on the rear of the car at the same time

[KC]

The contact points between the bulb and the socket may be becoming corroded. Pull the cover and remove the bulb, any oxidation will cause the light to get progressively dimmer. Just clean it up with an emery board or some scotchbrite and it should be good as new, if it is just corroded.

[Bluebottle]

Hmmm.... could be that the bulb is becoming blackened on the inside (they do that, it's a bulb thing...)
While you're in there checking the bulb, see if there is any corrosion or dirt on the contacts, the ones where the bulb fits and also the ones where the cable is plugged into the light cluster. I hard- soldered the wires onto the light clusters of my old Escort, they had corroded so badly that the currant coldn't find it's way to Ground, resulting in a very odd display, all caused by a dodgy boot lid seal letting in water which dribbled into the light clusters (also seen on old Ford Sierras!)

I'm sure I've heard of Corsa's blowing lights before...
A loose contact could cause the fuse to blow- most likely place is the bulb holders themselves, probably not in the 'precision connector' league!
Let us know what happens...

[Carrie]

Contact points look fine, already checked that
Have thought in the past there's been a loose connection on the lights on that side, but haven't managed to track one down.
In fact, because of the trouble I've had with lights on this car, fuses, wiring, connections etc have all been checked out a number of times.

As regards lights blowing frequently on Corsas. Well, I reckon I'm well into double figures for the brake bulbs I've replaced on the rear of the car alone and I've had it 2 1/2 years (compare with the Nova I had for 5 1/2 years and replaced 1 sidelight). Anyway, I did actually query with Vauxhall a while back about the rate it ate bulbs at because sometimes a bulb will only last . They said that when my model of Corsa was introduced it took 3V bulbs, but 12 months later, Vauxhall upgraded the spec of Corsa bulbs to 5V and so that was their only reasoning as to why it might be happening, but they didn't offer any solution.

Knowing from experience of lights on this car, I'll probably never get the answer to what's happened with the lights this time. I gave up trying to actually work out what it was doing with its lights a long time ago

[TimD]

My most practical advice would have been "Ask Bluebottle", but I'll simply add that my Corsa eats brake light bulbs, but ONLY brake light bulbs.

I've now got through seven. Bulb number five was weird. It came out of the holder and the whole of the interior of the bulb was coated in a creamy residue, not unlike limescale. Very odd.

Regarding the bad connection to earth being encountered on old Sierras - I'm happy to report that the Mondeo is keeping up with tradition. I followed an "L" reg example (1993) last week, which was coming up with a wonderful display. Every time the driver braked and used the indicator, the red running-lights would wink instead of the orange turn signals, and the reversing lights would shine brightly as well as the brake lights.

[Carrie]

Originally posted by TimD
Regarding the bad connection to earth being encountered on old Sierras - I'm happy to report that the Mondeo is keeping up with tradition. I followed an "L" reg example (1993) last week, which was coming up with a wonderful display. Every time the driver braked and used the indicator, the red running-lights would wink instead of the orange turn signals, and the reversing lights would shine brightly as well as the brake lights.

You sure that was a Mondeo, Tim? You've just described an identical light array to the one I encountered on a Renault Laguna this evening

[TimD]

Spooky! But yes, I can confirm it was a maroon 4-door Mondeo!

[Chris Y]

Do they do the 'fish tank' in the rear lights as well as the Sierras, and Mk3 Escorts did? (like BB pointed out )

[Ray Bell]

When the earths are poor, the lights will find their earth through any leak-path they can (electrical leakage, I mean) and this accounts for the other bulbs lighting up instead!

The 'creamy' globe has had its filament burn away and leave that residue instead of the black, probably made from a different type of tungsten alloy or something. I've seen plenty like that.

With the news that there are 3V and 5V globes, I would have thought it logical that you ensure you get the 5V, but I don't understand why they would use globes of that voltage...??

By the way, when cleaning up the holders and so on, be careful not to rub away the zinc or whatever plating, which is there for protection against rusting. A difficult balance, I know...

Can you check on that 3V and 5V thing... is that a thing makers do these days?

[Red Dog]

Hi Carrie,

I reckon a faulty earth connection is the problem. The majority of cars use the car body as the 'earth' circuit - more properly termed the neutral - and the connections from the lamp cluster to the car body are where they tend to fail. I don't know how your vehicle is wired but it may have an earth/neutral cable from each cluster running to a point on the body nearby. It might be that you have a damaged cable with some of the strands severed (has a trailer socket ever been fitted or some extra lights?)

Try swapping the lamps from side to side of the car (I am assuming one side is okay)

The proper way to check what is happening is to put a voltmeter across the supply to your lights. It should be getting 12+ volts from the battery. (It could just be your rear lights are supplied via a relay and this might be faulty but the other lights on the same circuit would be similarly affected.) Before you start, check what voltage the battery has with the engine off and then running. Should be 12.5 to 13 off and about 13.5 or so running. The figures should be similar at the rear lights. If they are not the same the dimness is caused by a loss of voltage. This could be live or earth fault but the earth can be checked by using a substitute earth which is known to be good nearby (a clean metal part) and the live by using a substitute good live nearby. If the voltage increases you have found the fault cable.



I hear what bluebottle says about blackened bulbs. I have never known a bulb to be so blackened that it was as dim as you say but you can easily check. It is caused by oxidisation of the Tungsten filament which coats the inside of the glass. When it gets like this its pretty well worn out anyway.

I'm not sure what Vauxhall are saying about 3 volt or 5 volt bulbs. As far as I am aware all cars have 12 volt electrical systems and although some instruments are regulated down, lights are 12 volt. If they were talking about watts then all rear tail lamps are a mandatory 5 watts with brake lights at 21 watts and anyway a lower wattage lamp would not blow quicker, it would just be consistently less bright.

If there is a charging system problem then your lamps would not enjoy being run at say 15 volts, but that's not something I've met. It would also tend to fry the battery and so on.

It is possible that the quality of the lamps may be suspect. If the inert gas inside the lamp is of poor quality, the filament will oxidise much faster and fracture. As you have said, these things should last for years.

[Bluebottle]

Originally posted by Red Dog

I hear what bluebottle says about blackened bulbs. I have never known a bulb to be so blackened that it was as dim

I've only ever seen it once, and I can't remember where- might have been on the Hurricane...

[Carrie]

Well, I changed the bulb. That blew a few more bulbs, changed those and the existing problematic bulb again. Working fine now. Thanks for the advice folks
I had reason to visit Vauxhall today to get fobbed off about what isn't actually covered under warranty, so once again used it as an opportunity to ask why this sort of thing happened with such frequency. The only response they could offer - It's a Corsa thing!

[Carrie]

On the subject of blackened bulbs, that's something I've encountered regularly on the Corsa, including this one. However, as others that have blackened have been darker than this one, I can't imagine that's why it went dimmer.