Sidelight feed from facelift 2014 rear cluster

[Edd 110 TDI Estate]

Spoiler

 

Hi,

 

Order if anyone knows how to connect a feed to a 7 way relay to power sidelights on a trailer?

I've check all connections and seem okay apart from sidelights/tail lights.

 

I tried to work out which loom wire goes tonwhich bulb wire on the lamp unit and came up with below.

 

From cars loom:

 

Black green indicator bulb

Black blue always on but feed to reverse bulb on lamp unit

Brown earth's 

Side lights brake light and fog all on Led panels plug, see below

 

Grey white to yellow on lampcluster  rear foglight

These Both act same same:

Purple red to white on lamp cluster 

Black Red to brown on lamp cluster 

 

The rely feed from grey white trigger outlet 2 for fogs all the time, but nothing happens on trailer board.

 

Can anyone label the cars loom plug for the driver side rear light please for me, ie colour and functions?

 

I understand not to connect black and brown wires from relay to allow relay to know its got a twin feed.

 

Thanks..

 

[chimaera]

Feed for the relay should come from a fused power supply from the fuse panel. Connection to the lights should only be for switching purposes. Any large current draw on a bulb connection could blow fuses or damage the BCM.

[chimaera]

You can buy the service manuals (which include the wiring diagrams) from Skoda at https://erwin.skoda-auto.cz/erwin/showHome.do

 

[Edd 110 TDI Estate]

4 hours ago, chimaera said:

Feed for the relay should come from a fused power supply from the fuse panel. Connection to the lights should only be for switching purposes. Any large current draw on a bulb connection could blow fuses or damage the BCM.

Hi yes I've done that, fused supply from drivers fuse panel to relay.

[Edd 110 TDI Estate]

Car is mk2 facelift superb.

 

I think I need to supply the fog and brake from the rh loom  currently from the left hand loom. Especially as the left hand side doesn't have a fog!  

 

I noticed the brake feed on lh is 1.4v until brake pressed then 13.2v

 

I noticed the right loom brake feed is 14.3v with sidelights on, and when sidelight and fog on. Then it's 14.6 when brake pedal pressed. 

I assume this shows the brake feed on the rh loom carries the side lights power and not the left loom. 

Therefore if I wire brake feed to the rh loom it should power sides! Will try tonight.

 

Looks like pin 4 on both sides is a power feed for the multi led part of lights to let it do its thing with the led stripe, powering them up and down etc to get side brake or fog.

 

Anyone concur? 

[chimaera]

It'll cost you less than a tenner to go on erWin for an hour and grab the Skoda wiring diagrams.

[Edd 110 TDI Estate]

So pin 8 is feed for fogs, it isn't shared its dead until fogs switched on. 

Swapping brake feed pin2 to right side rom left didn't change a thing.

 

Therefore I can only conclude pin 4, which is always 12v, and changed to 14v when lights are on is the side light feed. 

 

This means then that you don't have to follow the shared feed info on the relay instructions (leave out black and brown) OR my trailer board doesn't have sode lights which I don't belive...! 

 

I'll try adding the black or brown from relay to pin 4seewhat happens but I'm guessing the side lights on the trailer will be on all the time and the draw will upset the control module to throw a fault. Let's see.

 

[chimaera]

The tail lights are powered/controlled from the BCM. If you get this wrong you could fry the BCM (you wouldn't be the first). A new one of those is expensive.

 

The subscription to erWin is a tiny fraction of the cost of a BCM. You get the factory wiring diagrams immediately (pdf download) and no more confusion or guessing.

 

I can't help you because the diagrams I have are for my pre-facelift 2012 and may not be the same as the 2014 you have. (Even year to year there can be minor changes)

[Edd 110 TDI Estate]

Good point, however I've just come in from finishing, so too late to save me.  

Nothings gone wrong yet, I connected the rh side light input from the relay to the pin 4 grey red from the  loom.

 

Everything now works perfectly in all conditions with all lights on etc. No other combination of inputs triggered the side light feed so this must it, I hope.

 

How long would it take to fry the control unit? 🤔 

[chimaera]

Pretty immediate if it's going to happen.

 

I avoided all this hassle on mine by using Skoda's wiring kit. Everything plugs in neatly, and you get some nice bonus features: ESP towing mode (can detect and correct sway), engine/transmission knows you're towing and can modify its operation accordingly, alarm will go off if the trailer is unplugged while the car is locked, you'll get bulb out warnings for your trailer too.

[Edd 110 TDI Estate]

So just to close this one off, pin4 was used as sidelights into the single black wire on the relay and it triggered both sidelights on the trailer. I towed for six hours and used every function without an issue. So all good thank goodness. 😊