brake light warning caused by brake switch?

[JUS3IN]

Alright people, ive been battling with an intermittent brake light failure warning light, i scanned the brake section on vcds and it says no response from controller so i cleaned the bulbs/holders/connections but still i get this warning randomly going off, its very annoying. so today i done a full scan on vcds (takes ages!) and it came up intermittent brake switch implausible signal, someone advised me before this code that its very unlikely the cause of my bulb warning?
im gonna order one in a moment anyway, what are the chances this is my problem?

 

[JUS3IN]

no one?

 

[JUS3IN]

This problem is doing my head in, cant be that rare a fault?

 

[Prawn]

Mine does it. Has done for years. Drives me insane. Never found a fix.

 

[JUS3IN]

really!!! every 2-5 min sporadically it does my head in, i read about adding wires and resistors to the relay to disable the bulb warning system, might go that route if i cant solve it... also read about an a6 where the guy opened up a 'black control box' in the boot that was full of moisture and sorted his, dunno if we have this black box thing or not?

can we not disable it in vcds?

 

[JUS3IN]

16955/P0571/001393 - Brake Light Switch (F): Implausible Signal
Possible Symptoms

• Malfunction Indicator Lamp (MIL) active
• Glow Plug Indicator Light active
• Brake Light(s) not working

Possible Causes

• Wiring and/or Connectors faulty
• Fuse(s) faulty
• Wrong Brake Light Bulb installed (21W instead of 5/21W)
• Brake Light Bulb(s) faulty
• Brake Light Switch (F) faulty

Possible Solutions

• Check Wiring or Connectors
• Check/Replace Fuse(s)
• Check/Replace Brake Light Bulb(s)
• Check/Replace Brake Switch (F)

Special Notes

• Brake Light Switches (F) have the reputation of breaking quite o

 

[JUS3IN]

wasnt the brake light switch, still drives me crazy....

changed the bulb holders and bulbs, changed the brake switch twice.

was reading through this thread, do the 8l have a j393 control module in the boot like the a4 in this thread?
http://www.vwaudiforum.co.uk/forum/...shows-brake-bulb-fault-but-bulbs-are-ok/page2

 

[Prawn]

Let me know if you get anywhere with this. Desperate to find a way to disable mine!

 

[JUS3IN]

Can we not open the relay and trick it with a bit of soldering ? Sure I read that somewhere?

 

[JUS3IN]

well here is a very intricate post about a guy who installed the bulb warning system on a mk4 golf, if only i was any good with electrics im sure this could be worked backwards? maybe?

http://forums.vwvortex.com/showthread.php?6131253-DIY-Audi-bulb-monitoring-system-in-a-MKIV!

 

[JUS3IN]

need some help with this, i know its a b5 a4 but would this work on an a3, this guy seems to know you can cut and earth two cables at the rear of the cluster to disable the warning?

http://www.audiworld.com/forums/a4-...lb-out-warning-wont-go-away-searched-2773371/

 

[JUS3IN]

wonder what we can do with pin18??? anyone?

 

[JUS3IN]

thinking about pulling the cluster and cutting the wire and seeing what happens, is this a bad idea?

 

[JUS3IN]

i had my third brake light off last night and cleaned the connection... where is the brake light control module on an 8l????

guessing no-one knows what voltage pin 18 needs to shut the warning up? cutting or grounding it will more than likely not fix my issue obviously, im more sober now!-)

what actually decides i get the warning do we even have a control module on 8l?? is it a relay at all or the cluster itself? no-one seems to know anything about this? may have to start an account on vw vortex....

 

[JUS3IN]

Not sure if anyone is actually following this but I will continue to post my thoughts here and hopefully I will eventually get somewhere...

Its occurred to me that 90% of the time now the warning is on as soon as I turn the ignition, so without me touching the brake pedal... Am I right in thinking the warning system must be getting the wrong voltage when the system shouldnt be active if you know what I mean? So we can eliminate it being a bulb problem, must be a short somewhere whether it be wiring, control module or cluster...

edit; its also worse in the wet, when i get a chance i think i will check the wiring in the boot shut...

does anyone have a wiring diagram?

 

[sparkyork]

Is this where you get a bulb failure light on the dis?

 

[JUS3IN]

yea, in particular the brake bulb one... come across it before?

 

[JUS3IN]

just found this in the parts database, so im guessing we have 2 relays, a relay for each side right ? and they are behind the fuse board is that right??

@Prawn what have you tried over the years? never taken it to an auto electrician?

http://www.partsbase.org/audi/audi-...tral-electrics-fuse-box-relay-carrier-relays/

 

[JUS3IN]

another thought after browsing this section is the tow/light board connector, this will obviously be tied into the brake lights and external....

hmmmm another thing to investigate, damd rain is halting progress on this.......

 

[JUS3IN]

well, got wet, had the high level brake light out again and disassembled it, removed all bulbs and refited. i also removed all the wiring to the tow connection, had the earth off by the sub and cleaned. still no change.
just bought both relays as they were cheap on the bay, not sure if i need one or both but heyho (bought 10 new leds for the centre brake too), are the relays behind the fuses?

 

[Prawn]

I'm following. Never done anything about it. Drives me insane. Please find a cure

 

[superkarl]

Wish I could help but I've no clue with stuff like this

 

[JUS3IN]

!-) you never done nothing prawn lol... i will get to the bottom of this. thanks karl, no-one seems to have, if i can then i know an a*** mobile mech near me who will if i can finally give in and front the dollar, hate giving up but im very close now.

 

[Prawn]

Interested to see if these relays fix it. I didn't even know there were brake light relays

 

[Perplexer]

I used to get random bulb warnings when pressing the brake peddle. Changing the brake light switch made no difference. Removing my LED sidelight bulbs and replacing with bright normal bulbs fixed it for me though. And they were CANBUS LED's too.

 

[JUS3IN]

mines on with the ignition permanently atm so im pretty sure its not a bulb issue, thanks for you input tho pal.
still waiting on the relays, changed all 10 led in the high brake light, no effect on the issue.
aside from this issue i fitted my hid's as when i facelifted i bought a3 lights doh.

wondered if the brake light warning could be effect by the other lights, guessing its a totally different circuit tho right?

 

[JUS3IN]

@sparkyork you never came back, do you have any clue matey?

 

[JUS3IN]

Update, damd relays didnt fix it, had enough. Its booked in the local car Sparky Friday after next.... Hopefully its a cheap fix...

 

[Prawn]

Grrrr. What relays did you change? The big 387/393 one above the fuel pump relay? Is there another one elsewhere?

TPS wanted £78 for a new one. I was going to take a punt on an eBay used one.

 

[JUS3IN]

Yep thats the one, above the brown wiper relay...I bought 2 eBay jobbies and they failed, on the flip side I should be able to tell ya what mine was next weekend.

 

[Av4nt]

God I had this on my first avant. Turned out to be a wiring loom melted through on the EGR cooler pipe lol. Didn't realize how awkward audi wiring was until that happened when things started lighting up and flickering that I thought weren't possible lmao.

 

[JUS3IN]

darn light went off a day before its due to be looked at, it was on solid for two weeks!!! the guy said it aint worth bringing it in if its off doh....

 

[rustynlc]

I had this issue on my previous 8l, I found resistance in the wiring, (swollen wire), I cut/re soldered the wire and it never came back on, I also had corrosion on the actual light clusters aswel, may not be your issue but worth a look,

 

[Prawn]

That's a highly plausible suggestion!

What section of wire did you'd replace? The whole run from pedal switch to clusters?

 

[JUS3IN]

bump, what wire and where? @rustynlc

 

[JUS3IN]

was it when the tow ball wireing is connected to the passenger rear?

 

[JUS3IN]

touch wood ive fixed it, went to my local car parts place today and bought two new bulbs and some electrical cleaner and while messing with the holders outside I noticed a very slight burn mark in one of the brake bulb holes, I bent up the prong in the bottom and it had burnt a hole through the insulating material and was obviously arcing to the spring below... dunno how but I must have got the holders mixed up when I changed them for the new/used ebay items and refitted the offending one.... I spun the piece so it wasn't touching the bulb and happy days been for a 30min drive and nothing...

@Prawn possibly fixed it.

 

[JUS3IN]

not ****** fixed.... piece of silver ****! I have somehow got it off again, held the reset button on the wiper stalk for ages and it went off... was also messing in the footwell aswell tho. yesterday when it was going nuts beeping on and off every 5-10 seconds was nothing to do with me pushing the brake pedal so it must surely be a short somewhere of corroded earth....

where are the brake lights earthed?

 

[JUS3IN]

it did occure to me that I can use an elastic band to hold the reset button in and this disables the system, I'm guessing I then lose all my din warnings tho which wouldn't be great if I had a brake fluid leak again or low oil pressure but its that annoying I have left a blue (to match my seats!-) band around the stalk ready to slide up if/when it plays about again.

 

[limbo118118]

Sounds like bit of a knightmare! My warnings just poped up twice in the last couple weeks....only happend since fitting new bulbs so i need to check it out too :/