Trailer wiring.

O.A.P

The tail lights wont work anymore on my trailer when plugged into my landrover defender , indicators' and break lights work as normal and the tail lights work too when plugged into my car.
I spent last Saturday striping back the loom to where the trailer socket wiring splices on to the main loom and replaced the socket itself, but it made no difference still no tail lights.
So what next relay or fuse ? if they failed nothing would work I think ?
I hope I don't have to follow the loom up until I find a broken connection ,
hopefully someone on here can advice me on the likely cause and save me another day wasted,
Thanks for any advice.

martinr5232

It sould be the black and brown wires you need to look at.
Have you checked for power at the plug ?? Have you checked the connection where the trailer wiring is connected to the vehicle wiring ??

Those are the first things to check.

O.A.P

martinr5232 wrote: »

It sould be the black and brown wires you need to look at.
Have you checked for power at the plug ?? Have you checked the connection where the trailer wiring is connected to the vehicle wiring ??

Those are the first things to check.

Yes that's what I done on Saturday and replaced the old plug because the old one looked passed it. The connections are fine at that point anyway.

martinr5232

O.A.P wrote:

Yes that's what I done on Saturday and replaced the old plug because the old one looked passed it. The connections are fine at that point anyway.

Have you checked for power with a circuit tester or multi meter ??

O.A.P

No . I plugged it into the car and it all worked fine, so I'm presuming that there is no power at the plug for the tail lights on the landrover.

martinr5232

Each side should be wired independantly but its possible it was wired the lazy way.
Check where the trailer wiring is wired into the vehicle wiring its likely done with scotch locks and you have a bad connection there.

O.A.P

martinr5232 wrote: »

Each side should be wired independantly but its possible it was wired the lazy way.
Check where the trailer wiring is wired into the vehicle wiring its likely done with scotch locks and you have a bad connection there.

Its soldered properly at the joint so that's not the fault, I went higher up the loom today and found one of the black red cables (landrovers right tail light) had chafed almost in half .


I was certain that at last I had found the problem but when I repaired it


So I have brake lights and indicators but still no tail lights. I also but a meter on them today

martinr5232

Have you tail lights on the vehicle ??

O.A.P

Yes working fine

mgbgt1978

Can you bring a temporary wire from the soldered connection to either the Brown or black conector at the socket ? Even just something wrapped around the solder and taped on will do.
If this sorts it then the 7-core cable is broken/stretched somewhere.

O.A.P

mgbgt1978 wrote: »

Can you bring a temporary wire from the soldered connection to either the Brown or black conector at the socket ? Even just something wrapped around the solder and taped on will do.
If this sorts it then the 7-core cable is broken/stretched somewhere.

Yeah Ill try that in the morning.
Its showing 2 volts at the plug when the lights are on, is this enough to work the tail lights (LEDs) ?.
Thanks for your patience by the way.

mgbgt1978

Unfortunately my LED expert (my son) took off for the Nurburgring (and Frankfurt Motor Show) last night . AFAIK the LED's would need more than 2v to work. I'd prefer to see 12v at the socket to be sure it's connected properly.

martinr5232

O.A.P wrote:

Yeah Ill try that in the morning. Its showing 2 volts at the plug when the lights are on, is this enough to work the tail lights (LEDs) ?. Thanks for your patience by the way.

There should be 12v at the socket. Is that wiring going to a module ?? You will need to trace the wiring between the socket and where it connects to the vehicle.

The Sidewards Man

You have the common lead of the meter crocodile clip onto a rusty part of your jeep, why are you not measurung from the earth on the 7 pin plug?

O.A.P

The Sidewards Man wrote: »

You have the common lead of the meter crocodile clip onto a rusty part of your jeep, why are you not measurung from the earth on the 7 pin plug?

I have just done that its now reading 6.7 for the left side but still 2 on the right.

mullingar

Firstly, check earth wire (white pin 3) to the chassis @0ohm.



Then check the voltages of pin 5 & 7 to both pin 3 and chassis

DWG

Hi O.A.P, If you are in the Midlands I will have a look at the Jeep for you. I don't have a business, its not for money. Just to help a man in need.

O.A.P

I replaced the old loom yesterday with one from landrover but it did not make any difference
It has me bet now and some garage can charge me for fixing it.
Electrics are great when you fix them yourself but when you cant they have to be the most frustrating ****ing part of any machine ever.

martinr5232

Where abouts are you ?? If your near meath ill have a look.

O.A.P

martinr5232 wrote: »

Where abouts are you ?? If your near meath ill have a look.

Thanks for the offer I'm in county Clare though,
Whats worse than paying someone to fix it is never finding out what the problem was.

DWG

O.A.P wrote: »

Thanks for the offer I'm in county Clare though,
Whats worse than paying someone to fix it is never finding out what the problem was.

Wish I could help you in person but you do have one more option, the little voltage you have at the wiring may be enough to open and close relays. if you wire realys in your landrover to give 12 volts to each of your trailer socket wires it may sort out your problem. Basic relays 4 or 5 pin should do the trick. pins marked 30 87 85 and 86 (87a in the case of 5 pin relay).

if you treat each circuit as a single relay you could do something like this.
Tail light
give pin 30 12 volts positive, 87 is your trailer socket pin 5
pin 85 gets an earth and 86 you link to right hand tail light.

This should give you a full 12 volts to pin 5 of your trailer socket and you will have a right hand tail light on your trailer
Pin 87a in the case you use 5 pin relay you could connect to pin 7 of your trailer socket giving you two tail lights.

you should really use two relays and do right and left for tail lights though.

If you already have break lights and indicators this may resolve the problem.

Hope this helps OAP

Best of luck
DWG

DWG

O.A.P wrote: »

I have just done that its now reading 6.7 for the left side but still 2 on the right.

Reading back, you may need to use just one 5 pin relay and use the left tail light wire to control the relay.

so wire from left hand tail light to pin 86 of the relay and pin 87 and 87a go to socket pins 5 and 7

Let me know how you get on.

DWG

hi5

The new socket is faulty, they come apart, two screws on the back from memory.
A loose or corroded wire inside I'd say.

O.A.P

Got it fixed yesterday .It took me an age to get a panel under the wheel arch off. Then I started striping the insulation tape off until I found one broken and two badly chafed wires.
Thanks for to all who tried helping me.

DWG

O.A.P wrote: »

Got it fixed yesterday .It took me an age to get a panel under the wheel arch off. Then I started striping the insulation tape off until I found one broken and two badly chafed wires.
Thanks for to all who tried helping me.

Congrats OAP. I am delighted for you. Nothing feels better that beating a problem that kicked your ass for a while. Well done my friend.

You won!!!!

Take care
DWG