Brake Light Problem

P

PaulB

Member
Does anyone have any ideas of a solution to the following or does it need to go to auto electrician?

1.6 fsi

When the cars lights are on the brake lights are permanently on (apart from the high level one), the high level one comes as well when the brakes are applied. When the lights are off the brake lights work as normal (I think!!)

Cheers
 
Have you changed the bulbs recently, could they have been inserted incorrectly? When the lights are on do the rear bulbs look brighter then normal?
If the bulbs are in correctly then it could be caused by a bad earth, to check this put the indicator on when the lights are on, do the lights remain bright when the indicator flashes?

Steve
 
Hi Steve, will check what you have said thanks for your suggestions. We haven't replaced bulbs but haven't had the car long so previous owners may possibly have. cheers
Paul.
 
Had a quick look, there's no dimming of lights when indicator on and they are definitely brighter than your normal driving lights. A fault code on the car is 18955 brake light switch F implausible signal sporadic fault, could this brake light switch be the fault making them permanently on when lights are on?
 
PaulB said:
Had a quick look, there's no dimming of lights when indicator on and they are definitely brighter than your normal driving lights. A fault code on the car is 18955 brake light switch F implausible signal sporadic fault, could this brake light switch be the fault making them permanently on when lights are on?
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Then brake light switch controls the high level LED brake light as well as the stop light bulbs, so it is surprising that they appear to be operating separately as you seem to think?

But the VCDS scan shows the intermittent fault as being the brake light switch.

I would suggest that you locate the brake light switch and try to pull out the plunger a little, because it sounds like it has lost its adjustment.

You could even try pressing the brake and then letting your foot slip off so that it comes back off sharply (all with the handbrake on of course).

This could possibly help to reset the throw of the switch, but the chances are you need a new switch, but worth trying the above before you spend the money.
But whatever you do, get someone to tell you if the brake lights are working as they should, the rear lights are quite bright and you may be thinking that the stop lights are on when they are not.

I would also check the bulbs, because if the filament for the stop light may have gone and that may be why you are thinking that the stop lights are not coming on when the high level LED lights are.

Steve B
 
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Paul,

It's possible, but if the high level light illuminates when pressing the pedal then it would suggest that it's working correctly?
The switch is prone to failure though, so it might be worth picking up a spare and swapping this over. I don't have access to a wiring diagram to check on the circuit connections but I'm sure others will be along to offer advice.

Steve
 
My money is on both bulbs being the cause.

Try replacing one first and I think you will find that it now has a stop light illuminating on that side.

Steve B
 
Thanks guys, will use your advice and look into it tomorrow and see if I get any further forward. Hopefully one of your suggestions helps solve it. Will let you's know either way, cheers your replies are appreciated.
 
Hi,

all three brake lights (left, right and high level) are connected together on a standard car (*) with one switch controlling them all. Thus they should be all on or off at the same time.
Although the dual filament brake / tail light bulb is keyed with asymmetric pins, it is possible given enough conviction to insert the bulb the wrong way round so the bright brake side comes on with the side lights and the dim side comes on with the brake.
I would check the sidelight and brake functions with the bulb holder removed so you can see the bulb and check if the bulb works better the other way round!

(*) cars with DIS and the bulb check system have each bulb (and filament for the brake / tail bulbs) wired separately to the bulb check unit. Here, the left, right and high level brake lights are driven independently so can be lit inconsistently, but only if the bulb check unit or wiring is faulty as there is still one switch signalling them all to be on or off. Having the bulbs the wrong way round still applies.

regards

Andrew
 
Hi, thanks for your replys, still trying to sort lights but will have to sort it one way or another now because MOT due :-(

Ive had a better look and have found out the following don't know if this gives you any ideas before I order a switch.

When the car lights are OFF and you press brake pedal the high level light comes on and the rear NORMAL lights come on (not brake lights).

When the car lights are ON the rear brake lights are permanently on, the high level light only comes on when brake pedal is pressed.

Thanks
 
PaulB said:
Hi, thanks for your replys, still trying to sort lights but will have to sort it one way or another now because MOT due :-(

Ive had a better look and have found out the following don't know if this gives you any ideas before I order a switch.

When the car lights are OFF and you press brake pedal the high level light comes on and the rear NORMAL lights come on (not brake lights).

When the car lights are ON the rear brake lights are permanently on, the high level light only comes on when brake pedal is pressed.

Thanks
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That REALLY sounds like you have somehow managed to get the stop / tail bulbs in the wrong way around!!

I can't think of anything else that would produce those symptoms.

Have you removed the bulbs and tried them the other way around. The bulb holders are not great and you can force the bulbs in wrongly if you get them wrong.

Steve B
 
Hi just got round to having a good look at problem, I swapped the right and left bulb over and cant believe it but its actually solved the problem. great stuff thanks for all your help, Paul.
 
PaulB said:
Hi just got round to having a good look at problem, I swapped the right and left bulb over and cant believe it but its actually solved the problem. great stuff thanks for all your help, Paul.
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They were probably in the wrong way around in the holders and when you swapped them around you have put them in correctly.

Glad that we were able to save you some money !!

Steve B
 
The asymmetric offset twin filament bulbs are not the easiest find (in Wales) and the more usual opposite offset ones do get forced onto place. I bought a box of ten bulbs. Seem to recall that I have eight in my Passat rear lights.

Worth getting a new brake light switch also. Genuine ones are cheap enough and could save that rear end shunt.:(
 
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meriafel said:
Worth getting a new brake light switch also. Genuine ones are cheap enough and could save that rear end shunt.:(
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Yes
Comparing cost to safety it is a no-brainier on this one.
Although the VCDS error inficating a problem with the implausible signal from the brake switch was possibly caused by the bulbs being inserted incorrectly.
You get the same error when both bulbs have blown.

But to be sure change the switch, a car pulling up in front of you when they gave no brake lights is a scary thing and very dangerous indeed.

Steve B
 
meriafel said:
Worth getting a new brake light switch also. Genuine ones are cheap enough and could save that rear end shunt.:(
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Good luck with trying to get a genuine one! Have to come special order from Germany - and there are none. I ordered one in December from Audi and still not delivered - Very poor Audi for a £8 switch that is a very common failure.
 
lac said:
Good luck with trying to get a genuine one! Have to come special order from Germany - and there are none. I ordered one in December from Audi and still not delivered - Very poor Audi for a £8 switch that is a very common failure.
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I ordered mine from my local Audi dealer and it arrived next day !!!
Last week!!!

Steve B
 
Birchall said:
I ordered mine from my local Audi dealer and it arrived next day !!!
Last week!!!

Steve B
Click to expand...
Maybe had one in stock Steve. You have a diesel? Mine is 1.4 petrol. Apparently due to the failure rate, Audi produces 4 different ones now. Car was in for its MOT when the thing failed and the garage ordered one from the local Audi dealer. They kept chasing it up but after 3 weeks still didn't have one. I ordered one from Stoke Audi in January but after 6 further weeks got this message

"Unfortunately we have not received the switch as of today, We have spoken to Audi Parts Support today and they have advised that the switch is on back order and there is a supply issue at the factory, we cannot at this moment in time supply any ETA for the part.

Every dealer in the country will have the same issue as ourselves, please be aware this is not an individual issue on your order".

So when I ordered the genuine one from Audi, I also thankfully ordered a pattern part from ebay, which arrived the next day. Gave it to the garage, fitted and MOT'd 5 weeks after the original date of the MOT. Car off the road due to pants part fiasco.

Very very poor Audi!
 
lac said:
Maybe had one in stock Steve. You have a diesel? Mine is 1.4 petrol. Apparently due to the failure rate, Audi produces 4 different ones now. Car was in for its MOT when the thing failed and the garage ordered one from the local Audi dealer. They kept chasing it up but after 3 weeks still didn't have one. I ordered one from Stoke Audi in January but after 6 further weeks got this message

"Unfortunately we have not received the switch as of today, We have spoken to Audi Parts Support today and they have advised that the switch is on back order and there is a supply issue at the factory, we cannot at this moment in time supply any ETA for the part.

Every dealer in the country will have the same issue as ourselves, please be aware this is not an individual issue on your order".

So when I ordered the genuine one from Audi, I also thankfully ordered a pattern part from ebay, which arrived the next day. Gave it to the garage, fitted and MOT'd 5 weeks after the original date of the MOT. Car off the road due to pants part fiasco.

Very very poor Audi!
Click to expand...

It wasn't in stock, they had to order it in, it was for a 1.4 petrol (the one that Simon bought from me recently)


But dealers do vary in competence and it sometimes depends on if they are part of a chain and if that chain is any good.

Sorry to hear that you have been unlucky with this, but a patern part like this should be OK, I have used a few of these from eBay and they have been fine!!

Good luck with the rest of the issues!!!

Steve B
 
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