B6 A4 Brake Lights Flickering

[JamieOS]

The brake lights are flicker rapidly on my B6 A4 when the car is off. I just noticed it when I saw its reflection in a window. It happens when the car is off and locked. I'm not sure if starting the car makes any different, but I'll check.

I replaced the brake light switch in the driver's footwell, but it doesn't seem to have done anything.

 

[vr6gordy]

Sounds like you've broken the new switch fitting it there quite a pain to fit properly

 

[JamieOS]

I can put it back in the car it came from and see if it is the cause. I can also just try taking it out of my car and having no switch for a day and seeing if still flickers. I've got a spare car to use while I diagnose this issue. To be honest, I don't feel safe driving this one until I know its fixed.

 

[vr6gordy]

There is your problem.. when you remove the break switch removing them breaks them you must fit a new one

 

[JamieOS]

Quality Audi design at its finest lol. I was hoping to avoid the long trip to the dealers, but I guess I can't.

It still seems odd that they would break in the exact same way and not just hold the brake light always on or something like that. I still think there could be more to it, so I'll see how ti gets on with no switch first.

 

[JamieOS]

Well I went and bought a brand new brake light switch. I had the lad at the parts counter check with the mechanic on how to install it and I followed his instructions to every last detail. It hasn't worked. I've got working brake lights, but they still flicker when the car is off. I'm lost at what to try next, other than letting the dealer have a go at installing it.

Anyone have any suggestions? I can upload a video/gif of the lights flickering if it is of any help to anyone.

 

[vr6gordy]

If it's not the break light switch it's got to be the relay

 

[JamieOS]

Which relay? Is there a brake light relay?

 

[vr6gordy]

There is no relay I've just found out .. try check for a bare wire behind the back lights ... have you checked the Clutch plunger also .. think there can mess with the break lights but not sure .. try getting car scanned. And see if it shows anything

 

[JamieOS]

Is there any part in particular I should scan? I've got a vagcom cable, but I'm running it on a Mac computer so VCDS crashes all the time, so I can never do a full scan.

 

[vr6gordy]

Run a full scan and see what it comes up with

 

[QuattroCalum]

Don't touch the clutch switch it also ceases to function after removal. Have you had any water ingress issues via the ECU box, water could be playing havoc in your fuse box connections which is next to the ECU aperture.

 

[JamieOS]

I don't think so, but I may as well check. I'd imagine more than just brake lights would be going wrong if that was an issue. The brake light issue is also intermittent, not constant, so its a fiddly one to diagnose.

I still haven't got it scanned yet. My laptop wont keep VCDS running long enough to do a full scan, so if anyone knows what modules specifically to scan, let me know because being able to scan one small thing gives me a better chance to scan it successfully because it takes less time.

 

[QuattroCalum]

I don't think so, but I may as well check. I'd imagine more than just brake lights would be going wrong if that was an issue. The brake light issue is also intermittent, not constant, so its a fiddly one to diagnose.

I still haven't got it scanned yet. My laptop wont keep VCDS running long enough to do a full scan, so if anyone knows what modules specifically to scan, let me know because being able to scan one small thing gives me a better chance to scan it successfully because it takes less time.

Could be a dodgy bulb, might be worth fitting a couple of new ones for all they cost. It's not good trying to trace faults like this, I had to replace the clutch and brake switch when I removed them to replace the drivers side heater flap, I was angry with myself for doing so, if I had only persevered with the fiddly bolt.

 

[JamieOS]

Could be a dodgy bulb, might be worth fitting a couple of new ones for all they cost. It's not good trying to trace faults like this, I had to replace the clutch and brake switch when I removed them to replace the drivers side heater flap, I was angry with myself for doing so, if I had only persevered with the fiddly bolt.

But would one bulb cause all 3 brake light units to flicker? The one in the back window is flickering too.

 

[QuattroCalum]

Try removing one bulb at a time and see if that does anything. Failing that it's going to be following wiring diagrams.

 

[vr6gordy]

Have you looked for a broken wire just behind the back of the rear lights ???

 

[JamieOS]

Nothing visibly wrong with the wires, but I'll double check.

 

[vr6gordy]

Just had a thought. Have you looked at the plug from the back lights ?? Connection might be loose in there