I've noticed that when I pull up behind people, just as I come to a stop, I often see the headlights dim for a brief moment, right before the car comes to a complete halt.

I can't think of why this happens - anyone got any ideas?

The only thing I could think of is that maybe while I'm braking and in gear, the engine is getting power from engine braking, and that when I disengage the clutch, the engine loses that impetus from the drivetrain, and there's a momentary blip as it drops, and then compensates by increasing it's revs by delivering more fuel... make any sense? I'm not convinced that the headlight dim coincides with a rev twitch or my clutch usage though - hard to tell.

You can replicate the problem by pressing the UP switch on the windows while they are still closed - you'll see the headlights dim as the motors suddenly suck power.

Welcome to hear any thoughts on why I often get it when stopping though..

Thanks,

B

Have you seen how bright the break lights are on the octy ?

I've often considered driving backwards with the breaks on ... I think I could see further :P

I've noticed that when I pull up behind people' date=' just as I come to a stop, I often see the headlights dim for a brief moment, right before the car comes to a complete halt.

I can't think of why this happens - anyone got any ideas?

The only thing I could think of is that maybe while I'm braking and in gear, the engine is getting power from engine braking, and that when I disengage the clutch, the engine loses that impetus from the drivetrain, and there's a momentary blip as it drops, and then compensates by increasing it's revs by delivering more fuel... make any sense? I'm not convinced that the headlight dim coincides with a rev twitch or my clutch usage though - hard to tell.

You can replicate the problem by pressing the UP switch on the windows while they are still closed - you'll see the headlights dim as the motors suddenly suck power.

Welcome to hear any thoughts on why I often get it when stopping though..

Thanks,

B[/quote']Yes have noticed the same thing, not bothered me though just thought it was down to alternator not spinning as fast thus not producing same output.

Yes, that (alternator comment) might make more sense.

Same as you, not a problem, just something I noticed.

In terms of general brightness, the lights on my 2004 Octy MkI estate are infinitely better than the lights on my 1999 Audi A3, they were pathetic.

Note seen the issue with the lights, but have seen something similar with the window up trick. Mind you I think the lights in my 2001 Octy estate are pretty naff (waiting for powerbulbs order to arrive). The car with the best factory fitted lights was my old 1989 Nova!

I put Osram silverstars in my Audi and they were very good; much cleaner, brighter light.

I found that the Citroens I used to have (BX, ZX, Xsara) all had excellent lights, I think most French cars have good lights - I guess it's to help when you go back to look for all the bits that fall off the car as you are driving along...

So glad you posted this - I thought I was seeing things!

Sorry I was being facetious ... but I guess the reason is as the others have said the drop in enging speed when stopping, combined with the extra drain of the break lights is causing the alternator to struggle briefly. I've not noticed it myself, but I have noticed it with the windows ... try winding multiple windows up at the same time ... they go much slower.

As Goochie said really! I thought I was imagining all of this, but good to know you all have it too!

Perhaps people find it hard to admit they feel a bit dim now and then. :P

If your battery is in a poor condition (ie underperforming cells) the alternator will only charge to a certain point. Thus when you apply heavy electrical loads such as window motor, your lights will indeed dim as power is being diverted. The electrical system on all cars are 'Load Balanced' so that switching between electrical loads should not have an effect. Get your battery and/or charging system checked.

if its a battery problem mine was supplied with a dodgy battery as it has always done it (now thats a worry) but with all teh extras i am running on my car since i got it i dont think that the battery is a problem in mine. It is due a service sooon so i think i will get them to check teh charging rate. Ta for the heads up

I put Osram silverstars in my Audi and they were very good; much cleaner' date=' brighter light.

I found that the Citroens I used to have (BX, ZX, Xsara) all had excellent lights, I think most French cars have good lights - I guess it's to help when you go back to look for all the bits that fall off the car as you are driving along...[/quote']

I'll agree the BX had excellent lights, but what ever fell off yours?

Mine got 250k miles and nothing dropped off, well apart from the squirel that hit the front bumper :P

Joking - nothing dropped off. The main thing it dropped was all the LHM fluid one day. That was fun.

Oh, and the time a loose battery connection meant that when I opened the window at 80mph on a twisty road, the engine cut out. That was fun too.

So, back on topic - (18 months or so since last post), anyone got any more idea on why this headlight dim happens? It still does it and it still annoys me.

Jat, can you elaborate on what you mean about the electrical systems being load balanced? There's just a battery with a finite capacity, an alternator with a finite output (particularly at low revs) and a load of circuits that can be switched on or off. When a circuit is switched on, small resistances in wires and connectors will cause a small voltage drop across the whole system.

If you're braking particularly hard, the ABS pump will draw a lot of current and lower the voltage a little, but it doesn't sound as though that's what's happening here.

Also, you might notice that steering whilst stationary also dims the lights. It's just the PAS using up some juice. Nowt to worry about.

Also, you might notice that steering whilst stationary also dims the lights. It's just the PAS using up some juice. Nowt to worry about.

The Octavia doesn't have the electronic PAS :P

So glad you posted this - I thought I was seeing things!

Me too - I assumed it was the front of the car dipping slightly as I braked and so the angle of the beam was changing...

i've noticed this too, dimming of the lights when sitting at traffic lights.

Mine also do this and have been since the day i got it (around 4 weeks ago) but now my engine management light has come on has this happended anyone else???

I put Osram silverstars in my Audi and they were very good; much cleaner, brighter light.

I found that the Citroens I used to have (BX, ZX, Xsara) all had excellent lights, I think most French cars have good lights - I guess it's to help when you go back to look for all the bits that fall off the car as you are driving along...

I agree the lights in the BX and 306 I used to drive were great, even better with silverstars or 30% brighter all weathers in

The lights will dim as the alternator is no spinning fast enough to

charge the battery............

won't hurt to have the drive belt tension checked.

A loose drive belt will run the alternator slower, therefore not charging your battery fully and also not being able to supply the power to your lights.

If I'm not mistaken, the headlamps shouldn't dim at all.

Oooh, and all this AFTER your battery has been checked and is fine.