Hi,

 

So it seems I have an issue with the tail lights on my 2006 Octavia vRS hatchback.

 

Picturing the 'C' shape of the tail light pattern: The top and bottom tail lights on both sides are not working. These are the dual-filament type bulbs. They still work as brake/fog lights, just not as tail lights. I DO still have tail lights on the extreme outer edges of the light clusters.

 

At the moment, i'm trying to locate a possible suspect fuse, but I don't see a tail light fuse listed in the owners manual.

 

I've inspected the relevant bulbs, and they all appear OK. No visual filament breakages, and the bulb glass is crystal clear with none of the blackening associated with a blown bulb. The contacts appear clean, and the bulbs do not feel loose in their sockets. Wiring and connector plugs to the socket boards seem good too. I'll try to obtain some new bulbs over the weekend, but I can't imagine the exact same bulbs burning out on each side at the same time.

 

Any ideas? Any advice would be much appreciated.

UPDATE...

 

I removed the lighting boards from the tail light clusters today and found that the connector plugs don't even contain the necessary wiring for the tail light function on these bulbs. No wiring has been cut. It appears that it was never even there to start with.

 

I've never seen a mk2 Octavia with just the outer 2 tail bulbs illuminated. Does this seem weird to anyone else? I'm considering contacting Skoda to make enquiries.

You're correct, all four bulbs on each side should be lit as tail lights.

 

It's quite common to only have 5 wires rather than 6 to each taillight on the Octavia. Although the bulbs are dual filament, it doesn't use the lower powered filament for the tail lights, instead, it uses the higher powered filament but dims it using PWM. If your brake lights and rear fog lamps are working, that confirms the fuses, wiring and bulbs are fine.

 

 

I'm not super familiar with how the lighting configuration is managed on the pre-FL, any chance you can post an autoscan from VCDS or similar?

Hi Langers, Thanks for the reply.

 

Unfortunately I don't have access to VCDS or other scanning methods. I'm completely new to VAG vehicle ownership and don't know any DIY-er with the necessary equipment.

 

What you say about the dimming the filament rings true with what Skoda told me this morning though. They're suggesting a possible BCM issue. Does this sound familiar?

The FL MK2 Octavia has a BCM and it's not unusual to have lighting issues if people mess with the coding of byte 18.

 

However, your 2006 pre-FL MK2 will have a CECM and CCM instead. I'm not sure how the lighting configuration is controlled on these, maybe @Eddie-NL can help?

Lighting is controlled by the CECM on the earlier Mk2

 

Has the CECM been changed?

 

does the car have aftermarket HIDs

Looking through the service history (and there's a LOT of it), i'm not seeing anything relating to lighting issues, CECM changes or similar. The headlamps are definitely halogen H7's.

***UPDATE***

 

The car spent the day with the Skoda technicians, who checked bulbs, fuses, wiring and connectors. They have said they would need to run a scope test to check the signal waveforms from the BCM. How long this will take to do is anyone's guess. For now, i'm running the car "as is", but will have to have the issue looked at sooner or later.

Ha-ha-ha.

 

I once played that trick to win a maintenance contract on a big site in central London, it impresses the hell out of anyone watching but in my case it was simply a visual prop, for the garage no more than words to justify more invoicable head scratching.

 

VCDS or their VAG diagnostics will tell if the module is communicating with the canbus,  an oscilloscope not that they will have one or know how to use it, is not going to be able to recognise the signals between the BCM and the rear light switching node amongst all the other data streams let alone decode them.

Edited 1 March, 20206 yr by J.R.

On 11/02/2020 at 09:26, langers2k said:

 it doesn't use the lower powered filament for the tail lights, instead, it uses the higher powered filament but dims it using PWM.

 

Actually I am a bit embarrassed now for my last posting because an oscilloscope could be used to measure the pulse width modulation although that would be from the rear lighting canbus node and not the BCM.

 

Mine is a 2006 pre F/L and it must use both bulb filaments because the trailer wiring relay module is triggered by the voltage applied to the individual lights.

Edited 1 March, 20206 yr by J.R.

20 hours ago, J.R. said:

 

Actually I am a bit embarrassed now for my last posting because an oscilloscope could be used to measure the pulse width modulation although that would be from the rear lighting canbus node and not the BCM.

 

Mine is a 2006 pre F/L and it must use both bulb filaments because the trailer wiring relay module is triggered by the voltage applied to the individual lights.

 

Hi J.R.

 

They did explain the pulse width modulation measuring, and with my limited knowledge of electronics, their explanation made sense, so I was happy with that. The car is due for a service in about a month's time anyway, so I might just leave it until it's booked in for that, and have them run the scope test at the same time.

 

I don't know about the towing equipment setup. But all the information i've found so far suggests that the 5-pin connection to the tail light board is common. That 6th pin always seems redundant. I have no idea if cars which are factory prepped for towing are wired differently through. It's all a bit of a mystery.

 

I've been strongly considering obtaining VCDS, but i'm not sure I can really justify the cost since it's unlikely I will be using it regularly. Other than that, are there any other arguments FOR getting it? Does it offer many other uses or benefits for the average home user?