**trailer brake lights not working**

[Warwick89]

Just put my camper on to take it for a drive and the brake lights don't work, tried the box trailer to check and those brake lights don't work either. Tried the missus car and the trailer lights worked.

I've unplugged the connections on the car cleaned and replaced and still nothing tested with a multi and it read 13.5 on the breake light pin so I'm at a loss.

If the pin is getting the power and there isn't anything wrong with the trailer what could be going wrong?

Thanks in advance

Warwick

[Warwick89]

I should mention I need to fi this tonight because It's the last chance I have before we hit the road

[lhurley]

The plugs not dirty, or lose? Both trailer and car side.

Is it a new plug?? Could be wired wrong.

[megatexture]

Did you check the earth pin ? Do the rest of the lights work ? Bit odd if its only the brakes

[Warwick89]

The plugs not dirty, or lose? Both trailer and car side.

Is it a new plug?? Could be wired wrong.

Plug hasn't been changed on either trailer and it's very clean

[Warwick89]

Did you check the earth pin ? Do the rest of the lights work ? Bit odd if its only the brakes

Yep all lights work on both trailers except for the brakes but they work when I use a different car so I has to be car side. Just confusing me because it's getting power and it's clean and tight I've redone all connections on the plug and still nothing. I'm about to smash something haha

[Warwick89]

I don't see how it could be an earth if everything else works. I'm at a lose now I don't know what to do

[mudnut]

Since the trailer lights work when connected to the other car, the fault is in your car. It could be a high resistance connection behind the socket, or where the wire taps into the brake light circuit, especially if scotch locks were used. Try a bit of crc or wd40 on the plug and socket, it sometimes works. Also check the resistance between the socket earth pin and the car chassis, it should be close to zero ohms.

[megatexture]

Ye not earth pin if the other lights are ok .
Is the brake pin firm in the female end and ring on the male it could be getting pushed away when you plug it up, just try pushing on them... Its going to be something simple and you will kick yourself lol

[gaddy]

Has it got those dumb a$$ scotch clips joining the plug to the the harness , they are renowned for failing to make a solid connection

Opps just saw mudnuts post

[kevin07]

seems to me your car has to be wired wrong check the brake connection v the one on your wifes car if same hmm I would run a wire direct from the battery to your brake light wire on the trailer and see whats happening

[Warwick89]

Ye not earth pin if the other lights are ok .
Is the brake pin firm in the female end and ring on the male it could be getting pushed away when you plug it up, just try pushing on them... Its going to be something simple and you will kick yourself lol

Haha I hope it's simple but I'd still like to figure out what it is soon I have so much to do and running out of time. Their both firm and can't be moved.

[kevin07]

seems to me your car has to be wired wrong check the brake connection v the one on your wifes car if same hmm I would run a wire direct from the battery to your brake light wire on the trailer and see whats happening and hopefully that wont work either then you will get an answer

[Warwick89]

Has it got those dumb a$$ scotch clips joining the plug to the the harness , they are renowned for failing to make a solid connection

Opps just saw mudnuts post

Nope looks like all connection are soldered. If it was a bad connection would I still get te 13.5v reading?

[Warwick89]

seems to me your car has to be wired wrong check the brake connection v the one on your wifes car if same hmm I would run a wire direct from the battery to your brake light wire on the trailer and see whats happening

I've towed with my car before actually only 2 weeks ago and haven't ever had an issue. Checked the wiring already and all good at the plug

[TPC]

As others have said, it is probably a bad connection where it is being tapped off, possibly with scotch lock (worst thing electrical ever invented).
You will probably measure volts fine until there is a load and then it will drop.

[mudnut]

Are the trailer lights LED or globes. If it is globes, the high wattage brake lights draw way more current than the others. And yes voltage can be present with a high resistance joint, but when current is drawn, most of the voltage is across that joint instead of the lights.

You beat me to the punch, Tony:)

[Warwick89]

Are the trailer lights LED or globes. If it is globes, the high wattage brake lights draw way more current than the others.
The light are LED

[mudnut]

Yeah, they don't draw a lot of current, but need a good connections to work properly. You might have to measure the resistance between the socket and the brake lights by taking a light assembly off the car.

[TPC]

If you take the cover off the plug and plug it in you can test the voltage while under load.

[Warwick89]

If you take the cover off the plug and plug it in you can test the voltage while under load.

It's a solid metal plug so I can't just take the cover off I'd have to take the whole casing off and then I don't think I'd be able to get the plug to mate

[TPC]

Have you tried tracing the wiring on your car back to where it is connected?

[Warwick89]

Started looks like I may have to take the draws out

[mudnut]

Place your bets:

A) Loose screw behind plug?

B) Bad connection at wiring loom?

C) Crimped or squashed wire

D) Corroded connection caused by water ingress

E) One of the above plus a below average earth on the trailer or socket.

F) Wiring that has been twisted together then taped over.

[TPC]

Started looks like I may have to take the draws out

I had a look at mine and the wiring is taken from the back of the lights on the bumper, do you have a GQ or GU?

[Hodge]

Mate I went through the same dilemma 5 days ago. Whoever wired up my trailer plug originally used those wire tap connectors or whatever they call them. Water got in, they got so badly corroded there was no metal left in the connectors. Absolutely atrocious job, those things are farkin' s***. They should be banned!
I ended up going to Nissan and buying a proper Y harness, plugs straight into the lights on each side and a earth crimp to chasis, no crimping or wire cutting needed.

[lhurley]

It's a solid metal plug so I can't just take the cover off I'd have to take the whole casing off and then I don't think I'd be able to get the plug to mate

Mine used to be one of those, if you take the screw out the back it will side back along the wiring. I also had similar symptoms to you, i ended up just redoing the whole thing with a new plug. no issues now.

[threedogs]

X2 with gaddy I've had nothing but trouble with lights working and not working on my trailer
my son soldered all connections for me. still the same ,,,,,,,,,,,,,,there was one more wire with a FRICKEN scotch lok on it.
re moved and soldered that joint , now all is good . point is never trust a scotch lok, solder every joint with shrink sleeve over it

You can buy trailer plug LED test lights from SuperCheap auto
do you have electric brake controller fitted ??

[gaddy]

So what was the out come ?

[threedogs]

all joins were soldered so basically one wire from globe to the battery works like it should now properly
plus I have electric brakes, everything works fine now.

[Fozzee63]

Agh scotch locks worst invention outright some have alloy prongs- alloy and copper great recipe for disaster.


Sent from my iPhone using Motorculture mobile app

[threedogs]

Point is every one should check your trailer connections, if you see a SCOTCH LOK turf it
cause it will fail, If you cant get under the back,,, next service ask them to check and remove any scotch loks they find