Road lights

[SimonB73]

Hi

I got a new car. A skoda octavia.

When i connect our van to the electric on it the indicators work fine but when i press the brake both indicators and the brake lights come on but not very bright.

I had a trailer on the car yesterday and it worked fine.

Also, i've had two other vans attached and they both have the same problem ours does.

My last car had two plugs for the electrics on the van but this one just has the standard black trailer one.

Should it work for a caravan? I'm just starting to wonder because it works fine on the trailer.

I've bought a replacement for the connector on the car but now that i've discovered that the existing one works with the trailer I'm not sure if i need to change it.

Would really appreciate some advice folks.

Cheers.

 

[Dustydog]

Check all the connections in the caravan lights. Something is shorting out or a bad earth.

 

[Pauljw]

Hi Simon , if You have tried 2 other vans connected and Your own one and the problem is recurring, I Myself would take the car to a towbar fitter and get it checked out .

Paul

 

[Woodentop]

Assuming you had 12N and 12S on the last car and now have a 13-pin socket, there is a difference between old and new.

On 12N/S wiring, whilst there are earths on both sockets they were generally commoned in the caravan with a 13-pin the caravan battery earth, the fridge earth, and the lighting earths are all kept separate. This suggests that there is an issue with the earth associated with the lighting.

Have you had the caravan rewired from 12N/S to 13-pin, or are you using a Y-splitter to feed the 12 and 12S from the 13-pin? 12N and 12S both used pin 3 for earth, or a separate earth on pin 7 for the fridge on later wiring due to the current drawn; 13-pin has earth on pin 3 for lighting, on pin 13 for battery charging, and on pin 11 for the fridge. By lighting incidentally I mean road lights - the internal lighting earth comes off pin 13.

If you are competent then some investigation with a (digital or analogue) voltmeter should show up the cause of the problem, otherwise take it back to whoever fitted the towbar.

Oh, and by the way, don't assume that either a dealer knows what they are doing or that it was not fitted by an outside organisation even if you ordered the car with a 'factory fitted' towbar. I had a Co car about 12 years ago with 12N/12S wiring which would not work properly. I had to take it (under instruction from the leasing company) to a different garage before it was fixed - the auxiliary wiring had not been fitted.

Some years ago a relative bought a new BMW with a factory fitted bar. We went to visit them on site and they commented that the fridge had not stayed cold during their drive from Lincoln to Wharfedale. I checked and found the grey cable from the 12S just tucked under the boot carpet and not connected to anything! So much for BMW quality?

 

[Sproket]

Would the OP tell us how old his van is please ..

 

[colin-yorkshire]

Would the OP tell us how old his van is please ..

hi, it shouldn't matter how old the van is as all the 12n plugs are earth wired the same,

as the OP is using the same socket as a stock trailer the socket cannot be 13pin, as a trailer plug will not connect to a 13pin socket with out an adaptor and he didn't mention using an adaptor.

the symptoms described are typical of a bad earth, most common on old fords. where the earth connector on one of the light clusters was corroded.

the most likely cause is the earth wire connection, why would it happen on 3 vans but not a trailer, well there are several reasons, one of which could be the position of the earth connecting point, a van uses a white wire direct to the car socket, but often a trailer will use the chassis as an earth in the circuit, as well as the white wire. therefore although the earth wire [white one] may be defective it will still find a path to earth through the ball and socket. a van which has no such arrangement would not.
I would suggest the OP starts by checking the earth wires for continuity both at the plug end and the socket on the car.

 

[SimonB73]

Hi all

Thanks for the responses.

The bolts on the connector for the car are rusted into oblivion. I think I'll have to cut through the connector body with a hacksaw to get it off!

I rewired the connectors on the old van and the old car so i should be ok with that. I just wasn't sure if i should mess with it after discovering the trailer worked.

Time to dismantle i think.

Cheers folks. I'll post back when I've done the deed.

 

[colin-yorkshire]

hi,
what you have to remember when testing electrical circuits it to think of electricity as being similar to water,
water will always find the lowest point unless it is contained, just as electricity will always find a way back to earth unless contained.
water will not flow down a pipe if there is a blockage, same as electricity will not flow if there is a break in the wire.
water will escape through any place it is not contained, just as a current will escape if there is a shortcut back to earth.
water will only flow if there is somewhere for it to go, just as electricity will only flow if the switch is on.

given this basic premiss it should be possible to understand how and why electrical faults occur.
given the scenario of bleeding lights from other circuits, [as the fault reported] one can understand why this happens.
given that most modern systems use a positive feed and negative earth under normal operation the current is fed from the battery positive, through a switch of some kind, to the component [the bulb] the electricity then flows out of the component [bulb] back to the battery negative [earth], the flowing current through the [bulb] heats up the element as it goes through and the bulb lights up. if there is no flow the bulb will not light. simple. eh.

yes but one then has to remember the water idea, if the current cannot flow through the bulb because the flow is restricted on it's way to the bulb it will not light up at all.
but if the restriction is after the bulb [on it's return to the battery] there is still current trying to pass through it, like water it will then try to find it's way back by any route [usually the shortest] and given that a light cluster will have a common earth point to return, it will test every route on the circuit by going backwards through all the other bulbs in the system at some point it will find a route back when it does [this takes less than a millisecond] the current will flow and as the new route is now though all the other bulbs they will light up also.
but dimly as the current flow is much less than it would need to make them bright.

if you have more than one bulb light up in a cluster where there are multiple circuits it is a sure sign that there is a poor earth connection somewhere, as this is the only reason the current would bleed through the other bulbs.

hope this helps
colin.

 

[Woodentop]

Would the OP tell us how old his van is please ..

hi, it shouldn't matter how old the van is as all the 12n plugs are earth wired the same,

as the OP is using the same socket as a stock trailer the socket cannot be 13pin, as a trailer plug will not connect to a 13pin socket with out an adaptor and he didn't mention using an adaptor.

the symptoms described are typical of a bad earth, most common on old fords. where the earth connector on one of the light clusters was corroded.

the most likely cause is the earth wire connection, why would it happen on 3 vans but not a trailer, well there are several reasons, one of which could be the position of the earth connecting point, a van uses a white wire direct to the car socket, but often a trailer will use the chassis as an earth in the circuit, as well as the white wire. therefore although the earth wire [white one] may be defective it will still find a path to earth through the ball and socket. a van which has no such arrangement would not.
I would suggest the OP starts by checking the earth wires for continuity both at the plug end and the socket on the car.

Er, pedant mode on.

Pre 1979 the 12S did not exist so pin 2 on 12N was allocated as 12V power to the caravan for lighting etc. After 12S came into existence the 12V supply was moved to it and pin 2 of 12N was reallocated as the rear fog light.

You could easily spot the mismatch between tow and trailer as the rear fog light of the trailer (if fitted) was permanently on.

Pedant mode off

 

[colin-yorkshire]

Would the OP tell us how old his van is please ..

hi, it shouldn't matter how old the van is as all the 12n plugs are earth wired the same,

as the OP is using the same socket as a stock trailer the socket cannot be 13pin, as a trailer plug will not connect to a 13pin socket with out an adaptor and he didn't mention using an adaptor.

the symptoms described are typical of a bad earth, most common on old fords. where the earth connector on one of the light clusters was corroded.

the most likely cause is the earth wire connection, why would it happen on 3 vans but not a trailer, well there are several reasons, one of which could be the position of the earth connecting point, a van uses a white wire direct to the car socket, but often a trailer will use the chassis as an earth in the circuit, as well as the white wire. therefore although the earth wire [white one] may be defective it will still find a path to earth through the ball and socket. a van which has no such arrangement would not.
I would suggest the OP starts by checking the earth wires for continuity both at the plug end and the socket on the car.

Er, pedant mode on.

Pre 1979 the 12S did not exist so pin 2 on 12N was allocated as 12V power to the caravan for lighting etc. After 12S came into existence the 12V supply was moved to it and pin 2 of 12N was reallocated as the rear fog light.

You could easily spot the mismatch between tow and trailer as the rear fog light of the trailer (if fitted) was permanently on.

Pedant mode off

yes that is correct, that is why I stated "12n plugs are earth wired the same," the aux wire [pin 2] was moved to the 12S plug on the later configurations. and pin 2 [blue wire] used for the fog lights. but all the other pins remained the same, for the road lights, and pin 3 continued to be the return wire [white] for the light clusters, and the only one fitted to the 12N plug.
it wouldn't have any bearing on the OP's problem though as the blue feed wire before and after the change still used the same earth return in the 12N plug.
the problem of light bleed over is a earth/return fault not a power feed problem.
colin.

 

[RayS]

I think that rather than replacing 12N and 12S i would convert to the current 13 pin system - far better engineered and reliable, This can be done fairly easily. Put a junction box inside the A frame of the caravan and take the caravan wires to it. Buy a short length of current 13 core and the appropriate plug and socket. These usually come with instructions and a connection diagram. It will look frightening at first but if you start from the centre connection and work outwards it is not as bad as it looks. Make sure the bare part of the connection into each pin are sound and that no 'whisker' escapes when connecting - these can short of adjacent pins with strange results. Make sure the cable seals are correctly installed when reassembling the plug.
Same procedure for the car wiring although you should not need ( or indeed use if you can avoid it) an intermediate junction box.
I've been caravanning quite a long time and reckon the 13pin system is one of the best changes that has happened.

 

[colin-yorkshire]

I quite agree Ray, the 13 pin is a better system, however if you tow other trailers besides the van. you either have to change the plugs on all the trailers to 13 pin or use an adaptor. I tried using the commercial made little black ones. most unreliable, but did make a patch lead comprising of a short length of 7pin wire a 13pin plug and a 12N socket. that worked very well. [still have it in the car] but converting the whole system and making new leads may be straight forwards but does take a bit of effort.