Guide: Fabia 5-brake light mod

[Basil]

Guide: DIY 5-brake light mod


Disclaimer: I do not know what the legalities of this mod are in the UK and in other countries. Please ensure that this does not violate any local laws before following this guide.
The 5-brake mod is as it says on the tin, a pretty simple wiring mod to light up the rear fog lights simultaneously with the brake lights, as well as allowing you to selectively use both rear fogs independantly when needed in foggy conditions. A simple switch allows you to turn off the mod when desired.


I’ve noticed that there are a few 5-brake light mods on US forums for various VAG vehicles. Most seem to be rather complicated but one fairly simple approach which I adopted for the Fabia vRS seems to work really well.


You need both rear fog lamps to be active, which on the Fabia is a simple matter of running a jumper wire 14-16 gauge from the empty terminal of the left hand side rear light cluster under the rear trim to the live corresponding right.

Fog bulb, bulb holder etc are already in place from the factory but there's no actual powered wire present!!! (There are threads on Briskoda on how to do this and you can use a Scotchlok connector on the relevant grey-white rear fog wire to join the powered rear fog to the opposite un-powered one) If you look at the small dark rear light cluster connectors, you'll notice that there is an empty "slot" on the Left side one (RHD vehicle). All you do is run a suitable single wire scotchlok-tapped into the corresponding powered side under the rear trim, strip the bare end, insert into the empty slot and then bend it into a little ball from the other side. A little solder applied to the end before insertion helps to make it stiffer and prevent any corrosion. It's not elegant but works well plus it saves trying to find the crimp-on mini terminal end from VAG.

To do this mod we use two magic items called diodes. These act like an electrical one-way valve, allowing current to flow in one direction easily but not in the other.
basic componenets.JPG
Radio Shack part no. 276-1144 contains the 2 diodes you’ll need, cost me the equivalent of £1. (Specifications: 3 Amp barrel diodes 220A surge/400A peak inverse voltage). Thanks to Mathepac for this UK info: the device code for the diode is 1N5404 , Maplin order code QL84F, price 0.17p each ( 0.27c in Ireland). I'm sure Peats or Radionics will also stock them

14-16 gauge wire, about 1 foot

A crimper, barrel or butt connectors and a soldering iron.
A scotchlok tap-in connector is slick but not essential.

Electrical tape or heatshrink tubing with a hot air gun

What you do is solder the diodes and the wire as per the picture below (the silver rings on the diodes indicate the direction of current flow, like an arrowhead):
diode pic.JPG

As you can see, current can flow to the fog lights either when the brake is pressed or when the fog light switch is on. It cannot flow in reverse (so no brake lights on with the fog switch or the fog light lamp on the dash illuminating every time you press the brake pedal).

Disconnect the battery or pull the relevant fuse (I didn't....)

After preparing your "mini wiring loom" you pull away the carpet trim at the rear to access the rear light cluster (Driver's side). Use a screwdriver to gently raise the tabs on the connector and slip it off. Pic below shows mini harness ready to crimp in.
ready to crimp.jpg
It helps to have SWMBO or a mate in the driversseat plus a small 12V lamp on a couple of wires or a multimeter to positively identify the correct connector wires before you start cutting! (The rear fog wire was grey-white and the brakes red-black on my Middle East spec vRS).

Then you cut the foglamp wire before the rear harness + jumper tap to the other foglight and crimp in the wire ends as per the picture; tap the remaining end into the brake light wire with the scotchlok connector. You do not cut the brake light wire at all. Diagram below shows the wiring, note you can insert almost any simple on/off switch to turn off the mod when needed e.g. for the MOT.


Hopefully this will decrease the likelihood of tailgaters ramming me from the rear courtesy of my 312mm brake upgrade! Total cost, about £1 plus some odds and bobs I had about!

Cheers!
Bas

[L-Y-K]

looks good! now make your front blinkers bcome your sidelights!! that would be cool

[Goochie]

I'm rather confused as to why you'd want to do this mod

[devonutopia]

Well, I "guess" more brakelights would be in theory better for making people behind you are stopping, but the legality of it is in doubt. I'm really not sure on the rules. How bright are brake lights usually, compared to the normal lights? If the power usage / bulbs were different it would put me off a bit.

The idea of it sounds cool from a safety p.o.v though.

[ScoobyChris]

Originally Posted by devonutopia

Well, I "guess" more brakelights would be in theory better for making people behind you are stopping

But how many times have you not seen the car in front's brake lights?

Chris

[cheezemonkhai]

But then you have cut your brake light wires or at the very least interfered with them , thus making the system as a whole less reliable (yes i know it's a furby , but you know what i am saying).

I wouldn't want to be cutting the wires and then putting diodes in as I think that isn't exactly the best solution. This is especially true with the introduction of lead free solder, which is much more fragile than the old leaded solder, which in it's own right wasn't what you would call reliable in a car environment.

[Goochie]

Originally Posted by ScoobyChris

But how many times have you not seen the car in front's brake lights?

Chris

Perhaps Mil can tell us

[Basil]

The brake wires are NOT cut - a scotchlok tap is used, there is no discontinuity in the brakelight wires themselves. The Foglight wire was cut.

Those from the Crimping camp in the great crimp vs solder debate can use 2butt connectors for each diode to crimp them to the wires.

The fog bulbs are 21W compared to 1W brake bulbs IIRC - MUCH brighter.

The Yank VAG forums (VW, Toureg, etc etc) are full of 5 brake mod comments - seems it goes down well there.

As for me, I'll see how it goes - looks flash from the rear and I do have a problem with drunken tailgater tourists at night.

Again - you are on your own if you decide to look into this mod =- as they say "Information for educational purposes only!"

Over to you all........................

PS - I was lucky to avoid an accident this pm, was driving sensibly - a truck came over from the wrong lane in front of another vehicle in front of me, causing us both to slow down suddenly to a near-crawl on a roundabout. A Sport Landrover behind me stopped just in time to avoid rear-ending me. Dunno but seems my newly-modded bright rear brake lights must have helped save my bacon!

[neilwilliams]

How would this mod affect the bulb failure warning system that's on the vRS?

It's certainly one way to give tailgaters a shock though!!!

[Dr Zoidberg]

It would be illegal in the uk as it wouldn't comply with the construction and use regulations.

[vindaloo]

Originally Posted by Dr Zoidberg

It would be illegal in the uk as it wouldn't comply with the construction and use regulations.

<bigot mode>

References?

</bigot mode>

Without checking on DETR's website I can't be sure. Issues would be brightness and positioning. You have to have a minimum number of lights in certain positions on the vehicle. After that, there's a certain freedom to customise.

OK... I found some stuff on t'interweb... Office of Public Sector Information

There may be a brightness/intensity issue as "stop lamps" for modern vehicles are to be in the range of 15-36 watts. There's no requirement/limit on intensity of rear fogs that I can find... So I s'pose it depends on the wattage of the bulbs fitted in the fog-lights.

Stop lamps have to be 400mm apart and more than 350mm above the ground.

J.

[Basil]

The rear fogs are 21W - so that would mean that this mod IS legal in the UK right?

In any case I've included the addition of a simple on/off switch in the diagram in case you want to switch it off to avoid an argument with authority (MOT testing time).

Cheers
Bas

[ScoobyChris]

Originally Posted by Basil

The rear fogs are 21W - so that would mean that this mod IS legal in the UK right?

According to the MOT regs here:

Rear Fog lamps**

• must not be affected by other lamps and not be obscured

Which may suggest it's not legal, however, maybe one of our resident MOT testers (Phil, where are you? ) could comment

Chris

[VRSPhil]

I think it looks quite smart. Similar to certain Pajero's and MR2's. The only thing which concerns me is the additional stress on the brake light switch which I'm told is not all that strong at the best of times?

[Basil]

Originally Posted by VRSPhil

I think it looks quite smart. Similar to certain Pajero's and MR2's. The only thing which concerns me is the additional stress on the brake light switch which I'm told is not all that strong at the best of times?

Surely the brake light switch triggers a relay?

The rear fog lamps can be turned on independently - they are not affected by the brake lights then. IF you turn them on in fog and hit the brakes, rear appearance is unchanged from stock before the mod.

If the rear fogs are off, all you have is additional (safer) rear brake lights that have a wattage below the maximal 36W limit mentioned above (they're 21W).

I've been running mine since the guide was first published - no probs....

The yanks love this mod - if you do a google search, and I've yet to see a post reporting a problem...

HTH

Bas

[Td-eye]

I've been meaning to wire up the second rear fog light for a while now and reading this I reckon I'll wire up the five brake light mod at the same time.

Thanks for the guide, it looks entirely safe and legal to me and it can only help to warn others when you are braking.

It's strange how some mods don't seem to catch on here like this & the "ventectomy" mod (which I know you have done) which are both very common in the U.S.A.

[VRSPhil]

So let me just clarify...

With fogs turned off you get 5 brake lights
With fogs turned on you get 3 brake lights but the two fogs stay on all the time.

When you have fogs on and press the brakes does it not short out? Or is that what the diodes are for?

[Basil]

Originally Posted by VRSPhil

So let me just clarify...

With fogs turned off you get 5 brake lights
With fogs turned on you get 3 brake lights but the two fogs stay on all the time.

When you have fogs on and press the brakes does it not short out? Or is that what the diodes are for?

exactly.

No chance of shorting - it's all +ve wiring involved and you insulate all connections so they don't rub on the chassis-

one diode prevents current back-flow so that you don't get the brake lights on when you turn on the two rear fogs,

The other diode prevents current back-flow so that the dash fog light indicator doesn't light up every time you press the brakes.

[VRSPhil]

Well I decided to do mine earlier. Took about 20 minutes to make the wiring up and fit it. Total cost was £1.04 but I already had the wire so perhaps £2-£3 if you didn't.



P.S. Mine is an Octavia and the wire coloures were
Fog light - Grey with white stripe.
Brake light - Red with black stripe.

Thank's for the guide!

[vrs180]

I dont wish to be a "spoil sport" but this mod is not legal.

It may also voide your insurance

Pity cos it does look good.