Bit of an odd one. Noticed that my right lower rear bulb (brake or tail?) is on constantly. Goes off when locking or unlocking car then comes back on about 20 seconds later. Anyone experienced similar?

Yes, but only when I had left the parking light on (indicator stalk to the right). See if the front parking light is on at the same time. Perhaps it is caused by a faulty indicator switch?

It's the tail / fog...

 

Yep its fog/tail. No noise when car door open which I get when I flick the indicator.

It's not and no, factory xenon. The plot thickens tonight, with the lights on, the right tail light is the brightest of the four bulbs (about twice as bright I reckon.)

Ok, the brightness is the same as the the left fog when I turn on rear fog lights. Anybody got any idea which colour wire this is in the loom or where it may be worth looking for a break in the wire?

Is the bulb fitted correctly & the correct one? only reason i ask is i had a fault on a friends fiat & it was all caused by somebody forcing in the incorrect bulb. 

Sounds to me like the wrong bulb, I've seen all sorts of weird stuff happen when a single filament is put in the place of a double for example.

I've also tried switching the top and bottom bulbs round as they appear to be the same.  I'll take the other side out and check it's right but I haven't changed bulbs recently.  They are both 21w/4w same as silvers picture above.

Seems a strange issue for sure...

 

Might be worth adding the car to your profile so we can see the age etc. I assume it's the 2006 vRS from VRSerious?

 

Probably worth getting a VCDS autoscan done to see if that shows any problems. If the wiring or bulbs were at fault, I'd expect some kind of a warning or fault code to show up.

Yep it's the 2006 VRS TFSI.  I'll have a look on the VCDS map and see if there is someone local that can help.  

Sounds like the car has been tweaked. The pre-FL MkII Octavia in the UK only had one rear fog light activated, the offside or drivers side.

 

You mentioned when you turned on the rear fog lights the nearside (passenger side) turned on?

 

This would suggest someone has already had the car hooked up to VCDS and activated twin rear fogs. If they have messed around with byte 18 then anything could be possible!

Edited 1 September, 20169 yr by silver1011

Boot all dry no signs of water ingress there's multiplugs in the passenger side behind the trim clipped into the floor I had a similar problem with a pre fl estate putting the high level brake light on

 If they have messed around with byte 18 then anything could be possible!

 

I didn't think byte 18 affected pre-fl cars? Only fl ones with a combined BCM rather than separate CECM/CCM?

Oh not sure, thought I'd seen byte 18 on VCDS when plugged into our 2008 pre-FL.

I'd imagine it has had both rear fogs activated but this would have been done years ago so can't see that this would suddenly have gone wrong.  The boot is bone dry.  I have taken off the trim between the two light clusters and prodded at all the wires trying to replicate the issue.  Currently the light will go on for a bit and off for a bit at random intervals as though a wire is just barely touching another and doesn't seem to be directly related to any other light being on.  I will try to find the multiplug next and see what condition that is in.