LED trailer lights wiring issue

[becchops]

hi all, got an issue with wiring new lights onto trailer, hope i explain this clearly enough and someone can help,

1, blinker, tail light and brake light works individualy on 12v power supply
2, connect all, but brakes, up to trailer, all good
3, as soon as i connect the brake wire, i lose the tail light
4, tested lights off trailer with 12v power supply again, and when i have tail lights connected, i am getting 12v coming back out of light on the brake wire???

Sounds clear in my head, not so sure about everyone else, thanks in advance

[DP GTP]

IF you have wired up everything as per standard wiring the its most likely a poor earth. It also depends on your trailer is wired for 5 pin or 7 pin, same goes for your vehicle.
Cheers
Daz

[XR Martin]

What vehicle?
Alot of late model cars have issues with LEDs

[becchops]

DP GTP - bad earth is what i thought, so i connected straight to trailer plug on 3 cars, and still same issue.

XR6 Martin - three cars have done the same, my SZ Territory, my dads 2011 navara and also his BA falcon,

Starting to think maybe faulty lights, not sure

[DP GTP]

You may have already done it....but perhaps disconnect 1 side of the trailer and see if 1 set of lights is causing the issue. Could still be a poor connection on 1 side.

[jmack]

Had same prob with boat tail clearance lights would come on when you hit brakes. Lights that use same leds just different voltage for brightness give feed back .voltage drops off when a load is applied as in car brake tail globes .

[foxtrot3]

Hi. You could try a 3 amp diode in the brake and tail light wires to each lamp or send them back to China and get some quality narva lamps that work first time, every time. Cheers MD

[ebv8]

are the light cheap ebay ones or bought from an autostore like repco or supercheap?
i have had similar issues with ebay chinese ones, the connections are just really poor and wires are way too thin
LEDs look great but only work on certain cars so replace them with regular lights maybe?
I have LED's on my trailers and they work on my VX Commodore fine but not on my brothers territory or a mates X5 so that just means i don't lend it out anymore which suits me.
My dads new Pajero needed a wiring loom mod so it can run LED lights on trailers

[randel]

Agree with the other guys - did you run an earth wire in the loom/plug?

[Itsme]

Originally Posted by becchops

hi all, got an issue with wiring new lights onto trailer, hope i explain this clearly enough and someone can help,

1, blinker, tail light and brake light works individualy on 12v power supply
2, connect all, but brakes, up to trailer, all good
3, as soon as i connect the brake wire, i lose the tail light
4, tested lights off trailer with 12v power supply again, and when i have tail lights connected, i am getting 12v coming back out of light on the brake wire???

Sounds clear in my head, not so sure about everyone else, thanks in advance

Are you also losing the car stop lights when applying the brake?
I think you might need load resistors to be wired with the LED's

[Crazy Dazz]

Originally Posted by becchops

3, as soon as i connect the brake wire, i lose the tail light
4, tested lights off trailer with 12v power supply again, and when i have tail lights connected, i am getting 12v coming back out of light on the brake wire???

So when you apply 12v to the Tail-light connection, the tail light illuminates, BUT you are reading 12v on the "unconnected" brake-light wire?
I'm assuming the brake and tail LEDs are separate?

SOUNDS like either the tail lights have been cross-wired to the brake lights, or there is a short to earth in their somewhere.

[vztrt]

Originally Posted by trublu

Are you also losing the car stop lights when applying the brake?
I think you might need load resistors to be wired with the LED's

I have LED tail lights on my trailer and it doesn't effect it (no special brand but that what it came with). I did have an issue with the brake lights not working at but that was the brake wire was rubbed through by poor installation by the trailer mob.

[Itsme]

Originally Posted by Crazy Dazz

So when you apply 12v to the Tail-light connection, the tail light illuminates, BUT you are reading 12v on the "unconnected" brake-light wire?
I'm assuming the brake and tail LEDs are separate?

SOUNDS like either the tail lights have been cross-wired to the brake lights, or there is a short to earth in their somewhere.

Could be crossed wired but no shorts to earth as he should be blowing fuses.

[Olbucko]

Originally Posted by becchops

hi all, got an issue with wiring new lights onto trailer, hope i explain this clearly enough and someone can help,

1, blinker, tail light and brake light works individualy on 12v power supply
2, connect all, but brakes, up to trailer, all good
3, as soon as i connect the brake wire, i lose the tail light
4, tested lights off trailer with 12v power supply again, and when i have tail lights connected, i am getting 12v coming back out of light on the brake wire???

Sounds clear in my head, not so sure about everyone else, thanks in advance

I had exactly the same problem, I removed the conventional tail lights that were working correctly, wired in the new LED Narva lights, tried all day to solve the above problem, then gave up and reinstalled the old lights which straightaway worked correctly.

Could the socket on the car be wired up incorrectly

Is there a sparky somewhere that can tell us what we are doing wrong

[burnz]

use a jumper lead and clip it to the chassis of the car and trailer.
if this works, then look for a poor earth in the wiring harness of the trailer and car plug side.

[becchops]

Originally Posted by Crazy Dazz

So when you apply 12v to the Tail-light connection, the tail light illuminates, BUT you are reading 12v on the "unconnected" brake-light wire?
I'm assuming the brake and tail LEDs are separate?

SOUNDS like either the tail lights have been cross-wired to the brake lights, or there is a short to earth in their somewhere.

yes you are correct, i have a earth wire in the loom from the plug, but get this it all works fine on my uncles 2013 ranger, go figure

[becchops]

would like to thank every one for their input, it has been great, i am getting a new set sent anyway, so we'll see if that makes a difference, will let you all know

[Cashie]

The issue is normally because the brake and tail lights share a common return (original lamp had a dual filament globe). You'll most likely need a diode on the brake light circuit.
What car is it and how is the trailer socket connected to the car (genuine loom)?

[Itsme]

Originally Posted by Cashie

The issue is normally because the brake and tail lights share a common return (original lamp had a dual filament globe). You'll most likely need a diode on the brake light circuit.
What car is it and how is the trailer socket connected to the car (genuine loom)?

Yeah all lights share a common return (earth/negative) and usually everything goes pear shape when the return has a break or poor connection.

Bit strange the lights work ok on another vehicle but not his, I think his trailer loom wiring has a fault & I'm backing it will be the earth wire.

[BPXR6T]

I put a new tail light on my trailer a couple of weekends ago. All the sudden tail lights start flashing, then nothing would work, the one indicator would work. So I stood there and shouted expletives at it for 15 minutes. Magically everything started working and has ever since. Worked for me...