Hi,

I have a strange intermittent fault on various lights.

When the fault occurs this is the status of the various bulbs.

Indicators - FNS OK  - FOS not working - RNS not working - ROS OK

Side & tail lights - FNS not woking - FOS OK - RNS 3 0f 4 bulbs OK - ROS 1 of 4 bulbs OK

Dip beam - NS OK - OS not working

Full beam - NS OK - OS not working

Fog light - FNS OK - FOS not working

Rear fog - Not working

Brake lights - NS not working - OS OK - high led bank OK

Reverse light - NS OK = OS not working.

 

First thoughts, could be an earth issue, from experience on older vehicles earth fault can throw up some odd faults.

But not sure why it would affect diagonally opposite indicators and a mix between O/S and N/S lights when there are various earth points around the vehicle.

 

According to the Haynes manual - the wiring diagrams show the lights are controlled from the 'On-board power supply control unit' but I find no mention in the electrical section as to its location. However there is a section about the removal of ' Vehicle voltage control unit'.  Are these two items one and the same? I really don't wish to access the Vehicle control unit unless absolutely necessary since to remove it requires stripping out most of the interior dash/centre console/steering wheel (unless I can just access the connectors and unplug/plug back in to see if fault clears with out a major strip down).

 

Has anyone experienced similar faults?

 

Thanks,

Dave.

The BCM (Body Control Module) controls the exterior lighting and is a 6"x6"x1" black box above the pedals in the drivers footwell. It has 3x 52 pin connectors in black, white and brown/beige.

 

Given the number of bulbs out, it's almost certainly a power feed to the BCM rather than a fault in the BCM. The Haynes manual may term the BCM as the 'on-board power supply control unit' but I can't be sure.

 

I'd be checking F16 and F26 in the engine bay fuse box - based on the 2011 owners manual I have here. I would expect one of them to show signs of corrosion, water ingress, overheating or maybe a microfracture...

 

If I remember correctly, some older cars did have issues with water ingress to the fuse box causing similar issues

Thanks for that, I'll delve into the drivers footwell after checking the fuses.

Will update with progress.

 

Cheers,

Dave.

Random example to give you an idea of what it looks like, obviously the plugs would normally have wires coming out but they've been cut off 

 

Remembered some search terms...

 

Seems F16 for 'Central control unit, right main headlight, right rear light unit' is the common one to fail:

- https://www.briskoda.net/forums/topic/444945-fuse-keeps-melting-in-engine-bay/

- https://www.briskoda.net/forums/topic/491362-anyone-else-had-this-fuse-melt-but-not-blow-might-need-an-engine-bay-fuse-box-for-an-fl-20-vrs/

 

- https://www.briskoda.net/forums/topic/447376-skoda-superb-mk2-fuse-melting/

 

Useful info.

 

Cheers,

Dave.

Update on unusual fault on lights.

The fault was indeed as Langers2K highlighted, the 30A fuse position No.F16.

Removed fuse box and wondered whether it was repairable rather than trying to source a good secondhand correct replacement or buying a new one.

I am definitely of the mind to repair where possible.

With the fuse box removed and all the fuses (inc the relay blank/bypass plate) and all fuse positioned noted/photographed, I pushed the steel anti-crush tube half way out of the fusebox. It was then possible to lift out the top half of the fusebox. The only thing stopping it from easily pulling out was that the overheated fuse holder had melted the plastic and partially bonded it to the fuse holder/connection. With the top half off it was simple case of cleaning the fuse contact surfaces with emery cloth and crimping them in slightly to increase the contact/grip on the fuse.

It all went back together easily, refitted to motor with new 30A fuse and tested ok.