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chickenstu

Trailer light puzzle

does not take much to puzzle me.

brought a new sheep trailer in may- lights all working fine

was rushing and plugged the trailer light socket into the car whilst the car head lights where on.

since then only the indicator lights work on the trailer, the fog light, stop and tail lights no longer operate

1/ all the bulbs work fine having visually checked and swapped them all around into the indicators sockets
2/ there is no fuse box on the trailer
3/ all the lights work fine on the car
4/ all the fuses are fine on the car.

I am very puzzled as to what is wrong- if any one can give some hints I would be grateful
redbelly

That is a bit puzzling. Wiring problems really frustrate me.
By now I would be checking each terminal on the socket with multimeter or suchlike and then testing each lead to the trailer lights for continuity.
Perhaps the first thing though is to make sure that the earths are good as bad earths can lead to some fairly strange results. It is not enough to rely on an earth through the tow hitch.
Will be interested to hear what you find.
sod

Agree with Redbelly said check earth. what shape plug just thought things are different in other countries?
Gareth

As redbelly mentioned a continuity check of all the wires would help to identify the problem.

A cheap multi meter with a buzzer on the continuity function, a couple of  lengths of wire and an extra pair of hands would be ideal.  

First thing to check is the socket on the car...... can a good reliable earth connection be confirmed with a test light or multimeter? Check each of the lights in turn at the car socket first.


On the trailer, damp and loose connections in the trailer plug are the first things to check for. Then check all of the wire connections at the bulb holders: Don't forget the front marker lights and the number plate light. If the trailer plug checks out and the connections at the bulbs look clean and dry the fault  is very often in the multi connector block

Here is a typical wiring diagram for a trailer in the UK.




Underneath somewhere on the chassis there should be a waterproof connection box that will look something like this, and is where you will need to check for corroded or loose wires.

Often the problem is in the connections at the multi connector block, and is normally due to corrosion caused by dampness or a loose connection.




However, some trailer manufacturers as part of a cost cutting exercise do not use these and just have a heat shrink covered connector block that usually causes more problems than it is worth. If the trailer is still under warranty then force the issue with your supplier. If it is not under warranty then I would advise you to fit a waterproof connector block. These are readily available for about 10.00 at Agricultural machinery dealers, car and truck motor part factors.
Lorrainelovesplants

If you have a 7 pin plastic plug on the trailer connection plug open this and look for loose wires - especially the earth wire(white), failing this look at the socket on the car and check for water ingress.

If you can borrow a light bar, plug this into the car - this will check wether the problejm is in the car end or the trailer end.
chickenstu

ruddy hell guys- thanks- I have got to go to work in an hour so will have a look at it tomorrow with all your hints. Re using another tail board to check  why did I not think of that   but I am to practicality or DIY what Boris Johnson is to trendy hair styles.
12Bore

What Lorraine said, I seem to have to reconnect the terminals everytime I use my trailer.  
diggerpete1961

This is a good tip I found out while working on e-bikes, not perhaps needed in this case, but did not warrant a thread of its own. sorry if a bit off topic

A low cost way of owning a heavy current DC ammeter is this :-

Buy a 75A, 75Mv shunt for about a fiver, eg this as I did.
http://www.ebay.co.uk/itm/75A-75m...tDomain_0&hash=item2a232513fa

Connect any basic multimeter that measures milli volts (Mv) (even the under 10 ones usually do)  across the little terminals of the shunt.
Connect from batt+ throu the big terminals to the load  (eg a glowplug)

Amps drawn will read directly on meter on a 1 to 1 basis (sadly only whole amps are displayed, not fractional parts. Max 75 A load. I used this to check individual glow plugs without having to initially remove all, showed me the bad one even tho it still had continuity throu it. Also have used it to show me amps being drawn under different loads when riding the e-bike I built. Verify reading if in doubt using a known wattage bulb & ohms law.
gwiz

As I only get asked to look at trailer lights when it's pitch black in the yard, I have found one of these quite usefull
http://www.ebay.co.uk/itm/7-Pin-T...ng_Travel&hash=item3cca43ba7a

It points you to the general area of whats wrong (usefull when the guys want to get going asap)
reasonable price and will also check the wiring on the vehicle as well.
sod

How does it work never seen one here   As my way is to take cover off plug and go across with a test light. Here all trailers just have plug 7wire cable to lights never seen a splitter box as Gareth showed. Would love to see that tester.
gwiz

It contains a small battery that will send current down the circuit to test the trailer. The LED's will tell you what part of the circuit isn't working. If you use it on the vehicle, it uses the vehicles power.

If I have more time to work on the trailer, and need to have a circuit powered while checking it, I have a box with switches to open a circuit individually-ie left hand indicator, right hand indicator, stop lamps, running lights and so on. It looks a bit like the gadget in this link:
http://www.youtube.com/watch?v=R7...X8xU_NWzhYPuxqP_ccGuQ&index=5

Although mine's more "El CHEAPO" than that.
chickenstu

All sorted

The fact that it had happened (or appeared to) when I plug the trailer onto the running car with its lights on was a red herring. Wires had come loose on the motor on the brand new tow bar fitted to the new car back in July. Mystery solved- not that mysterious really

Thanks for all the help.

Stu
12Bore

chickenstu wrote:
All sorted

The fact that it had happened (or appeared to) when I plug the trailer onto the running car with its lights on was a red herring. Wires had come loose on the motor on the brand new tow bar fitted to the new car back in July. Mystery solved- not that mysterious really

Thanks for all the help.

Stu

Ahhh, when I had a tow bar fitted to my previous car, the installer failed to uprate one of the fuses in the car, upshot was that when I set off on holiday at 6 am the following morning the fuse blew when I used the indicators. Curiously, the indicators still worked, but the dashboard electronics didn't...
chickenstu

Curiouser and Curiouser....
gwiz

Curiously, the indicators still worked, but the dashboard electronics didn't..

Seperate relay, maybe.
Modern cars are a frightmare...
My 307 estates wires are not colour coded. It's horrid trying to trace a wire on it.
12Bore

It was a Fiat Marea estate, Italian car and bike electrics have something of a reputation...
chickenstu

ducati tastic!!
sod

gwiz thanks for that some workshops have such a thing here, will have to get sorted and make something  
rhino

12Bore wrote
Quote:
Italian car and bike electrics have something of a reputation...

Not as bad as landys,
they have lighting courtesy of Lucas prince of darkness  
Gareth

rhino wrote:
12Bore wrote
Quote:
Italian car and bike electrics have something of a reputation...

Not as bad as landys,
they have lighting courtesy of Lucas prince of darkness


     I like that a lot............ gonna steal it.  

I remember the totally dire state of the wiring looms on series II, series III, Stage, and the first defenders way back during my apprenticeship and improver year.
12Bore

rhino wrote:
12Bore wrote
Quote:
Italian car and bike electrics have something of a reputation...

Not as bad as landys,
they have lighting courtesy of Lucas prince of darkness

 

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