Lights oddity

[Len_Cuff]

More car than caravan problem but wondered whether the wealth of knowledge on here might help me!
My tow car - a Vectra has the genuine Vauxhall wiring fitted so I can't see how that could be wrong as it simply plugs into the Rear Electrical brain. What happens is that when I brake, all the sidelights and the brake lights come on. If I switch the side lights on then just they light up -- no brake lights and when I press the brake pedal the brake lights come on!! It's not the van wiring as it does the same thing when I use a trailer board and another car works as it should. Anyone ever seen this before. No big deal as it means I actually have 'extra' brake lights but intrigued as to why it does it.

 

[WoodlandsCamper]

Looks like you may have a bad connection the car socket, possibly an earth wire.

 

[woodsieboy]

I think there are some cars that light up both lights and brake lights under sudden heavy breaking, designed to warn the car behind

 

[ProfJohnL]

I have seen this on on some non UK spec vehicles, but it doesn't feel right for a UK vehicle. I think you should get the car checked, it might be a symptom of another problem.

 

[CyberCynth]

I too sometimes have a problem with lights when the caravan's in tow. Occasionally the reversing lights stay on on the caravan, even when the unit's parked, the engine's switched off and I've left the auto stick in the 'Park' position (as one does). I found by a process of elimination that if I disconnected the grey plug, the reversing lights went off. The 'van is going in for repair anyway soon, so will see if the engineer can get it sorted out then. Probably illegal to drive around with the reversing lights on all the time? Not to say disconcerting for following traffic!

By the way, twice recently my black cable has become disconnected from the socket on the car, damaging it enough to render further travel illegal. I know the first event was due to a very tight right-hand bend, which pulled out the wiring from the plug, but I don't know what caused the problem on the second occasion. There must be a fool-proof way of attaching these cables without risking mis-haps of this sort? Part of my problem is that I have a 13-pin plug on the towbar and a 7-pin plug on the caravan, so have to have an adaptor. This means there's always a problem trying to anchor the excessive amount of cable so that it doesn't drag on the ground, but I think in my effort to stop it doing that, I am not allowing enough slack, hence the two episodes I've encountered recently. Anyone got any ideas?

 

[woodsieboy]

As you have 13 pin on your car I suggest converting your van to 13 pin,we used to use an adaptor and like you we had problems, cable dragging on ground etc,since converting to 13 pin no more problems.

 

[Raywood]

Sounds like it is possibly a short circuit in the plug. I did have a similar problem some years back when the headlights came on when I braked. The problem was a short circuit in the plug.

 

[Dustydog]

This does sound like a classic earth fault.
Check all the earth points including the earthing point on the car.

 

[CyberCynth]

Thanks for that, guys. Has anyone any idea how much it is likely to cost me to have the 'van wires converted to a 13 pin plug? Is this a job your average Approved Caravan Mechanic can do? (Fortunately, thanks to Damian-moderator on this site, I found this chap on-line, only a couple of miles from me) I have got the 'van booked up with an Approved outfit for 4th August. I'm hoping it won't cost me an arm and a leg

 

[CyberCynth]

As you have 13 pin on your car I suggest converting your van to 13 pin,we used to use an adaptor and like you we had problems, cable dragging on ground etc,since converting to 13 pin no more problems.

I can't understand why there is such a long piece of cable on the adaptor, the makers must realise the added length causes problems?!

 

[Len_Cuff]

Just to clarify my original post, car is fitted with 'standard' twin electrics as per installed by vauxhall. I'm using a convertor to the 13 pin on the van but even when I try a normal 7 pin trailer board it does the same thing - very confusing!!

 

[colin-yorkshire]

Just to clarify my original post, car is fitted with 'standard' twin electrics as per installed by vauxhall. I'm using a convertor to the 13 pin on the van but even when I try a normal 7 pin trailer board it does the same thing - very confusing!!

hi Len,
it's not too confusing once you understand how electrics work!! simple tests will establish what is wrong,
you have done the hard bit testing with another board this establishes there is little possibility that there is anything wrong with the van electrics or the converter lead as the fault exists on both user items (van and board) the chance that both have the same fault is very unlikely.
so it must be the car plug!! I assume the vauxhall wiring is the flat cambus system by your description. so a fault here while this is possible, is also unlikely so the only 2 weak points in the system is the earth, or where the wires go into the plug, again I assume the indicators work correctly, or you would have said not. these use the same earth point.
so there must be continuity of current,
this therefore points to the wiring of the plug in so much as two of the wires "stop and tail" circuits are shorting, either by a loose strand or a frayed wire, that can sometimes happen with use, as I do not know how new the system is or how long the fault has existed, but this sounds the most likely cause, this is only a calculated guess of course based on the information provided, but testing would establish the true fault.

 

[Len_Cuff]

OK while I agree that something is wrong, it can't be the side and brake lights shorting together because as explained, I can turn the side lights on and they work fine - NO brake lights - and then while they are still on, the brake lights work fine. It's only when the side lights are off that they come on when I press the brakes. So that's even more confusing!!

 

[johnandrew70]

Thanks for that, guys. Has anyone any idea how much it is likely to cost me to have the 'van wires converted to a 13 pin plug? Is this a job your average Approved Caravan Mechanic can do? (Fortunately, thanks to Damian-moderator on this site, I found this chap on-line, only a couple of miles from me) I have got the 'van booked up with an Approved outfit for 4th August. I'm hoping it won't cost me an arm and a leg

Converting the van to 13 pin is simple you can buy a 13pin plug with twin inlets the wiring diagram is printed on the packaging.

http://www.ebay.co.uk/itm/SEALEY-TOWING-PLUG-13-PIN-EURO-PLASTIC-12V-TWIN-INLET-TB54-/111355160907?pt=UK_Recovery_Tools&hash=item19ed48e94b

 

[Raywood]

I cannot see it should be expensive but I would get a quote first so there are no surprises. Sounds less than an houys work plus a few cheap bits.

Thanks for that, guys. Has anyone any idea how much it is likely to cost me to have the 'van wires converted to a 13 pin plug? Is this a job your average Approved Caravan Mechanic can do? (Fortunately, thanks to Damian-moderator on this site, I found this chap on-line, only a couple of miles from me) I have got the 'van booked up with an Approved outfit for 4th August. I'm hoping it won't cost me an arm and a leg