Hi,

I've fitted a towbar to my '56 octavia 4x4 and now i'm trying to wire up the lights but i'm having some problems working out what wire is which. Haynes is no use. None of the info i've found is even close to the colour coding of my light cluster.

Is there anyone(other than the guy who put it together) who knows whats going on back there?!

I'm not much of an electronics guy so i was hoping it would just be a case of match the wire colours and away we go!

Any help would be appreciated,

Many thanks

Martyn

The whole system is far more complexed for wiring a tow bar now, nothing seems to match up. You may be best taking it to a tow bar fitter or get a mobile fitter. When mine was fitted the wrong socket was put on, OK the dealer arranged for the towbar fitter to come to my house and rewire the correct socket (13 pin) I took a look at the wiring loom and was totally lost.

I installed a bypass relay to my 07 hatch and the wiring was trivial. The instructions on the relay told me the colours i needed to splice into, it (the document) was octavia specific. Got the towbar and kit from PFJones.

I'll have a look when I get home and see if I can find the document and post the colours.

Edited 11 April, 201214 yr by kenmc

I would not panic. The light cluster has one wiring block connection with IIRC five wires running into it. One is earth (probably brown). The others are for side lights, indicators, brakes and reversing. (The car uses some sort of CAN-BUS magic to make the blubs glow brighter for fogs without using a separate wire).

So all you need to do is get a circuit tester for a couple of quid and test for a current on this connection block. Obviously, you will need to switch on different lights one at a time.

Once you have them figured out, (lights, indicator, brake and reverse) you will find the wires have the same function in the same position in the wiring block connectors for both sides but different colours in each light cluster. So, for example, reversing lights on mine are: Black/blue for nearside and Black/green offside. Wiring for both clusters are accessible where the loom splits under the nearside light cluster. This means that you can splice into the offside indicator's wire close to the nearside of the car.

I'm sorry I didn't make a note of the other colours when I did mine. In any case the colours seem to change over time so the instructions I got from PFJones didn't get me all the way there. It is best to probe them with the tester to make sure.

When you connect the relay, and if you have the right CAN-BUS compliant "Smart" Relay, neither the brake, nor Fog wires to the relay from the car need to be connected. When the car brightens the bulb for either brakes or fog, the relay senses this through the side light wire and supplies power to the wire (brake or fog) on the towbar plug.

There is a thread here: http://www.briskoda....towbar-wireing/ that kemmc and I contributed to with a litle more info. HTH

Right, have the documentation. It says (Skoda Octavia Hatchback 2004- ):

Lights...........Vehicle Wire Colours

-------------------------------------------

LH Flasher.......Black/white

FogLight.........Blue/Yellow

RH Flasher.......Green/Blue

RH SideLight.....Grey/Yellow

Brake Light......White/Black

LH SideLight.....Grey/Mauve

Reverse..........Black/Blue

These matched exactly to my car, but there's no guarantee they'll match yours of course. But it should be very simple to trace them back from the lights to see what colours they are, if not as above.

Edited 11 April, 201214 yr by kenmc

kenmc! i owe you a pint next time you are in the angus area!

those are the same wires in the back of my car. tried it this eve and it works a treat! many thanks.

thanks for the info friendlyfire, i havent fitted the relay yet because it says i need to run power from the battery through the fuse box.

i connected up my trailer and everything seems to work ok. is it always necessary?

The purpose of a relay is to take power from the 12v system and give it to the trailer lights. It takes a signal from the car wiring in order to decide which light to set to on.

Because the ammount of current it takes from the wiring loom for a signal is so low it doesn't set off errors in the car's computer.

If you don't use a relay you may get errors and the car's lights might flash too slow or dimly. You may cause damage. Your car might be old enough to cope but then again it may be young enough that it needs protecting with a relay.

Glad I could help. To be honest I'm surprised it worked without the 12v supply at all!

I ran my 12v from the fuseboard (just plugged a spade connector into a constant 12v, via an inline fuse), under the steeringwheel, to the pasenger footwell and then just pushed it up under the trim all the way to the boot to the relay. Hardest part was trying to get it from the rear passenger footwell into the boot, to route the cable.

Oh wait - I think i understand - you plugged your towing socket directly into those wires, without the relay in place at all? One thing the relay also gives you besides low-loaded switching, is the audible buzzer on turn indication, which I believe is a legal requirement when towing, so you can identify that the trailer indicators work. It's annoying as f*ck though, esp as I only use mine for a bike rack!

Edited 11 April, 201214 yr by kenmc