Trailer lights - not an LED related question...

[Jpdv]

Hi folks, and my apologies - I'm sure this has been covered somewhere else, but I'm without my reading glasses atm, and have given myself a headache trying to find a relevant thread...(is it me, or has the search function just changed? - I'm finding it much less intuitive...) So an ageing bloke would welcome advice on the following:

1. 2016 MY D4, with an untouched factory rear socket setup.

2. Just purchased a second hand trailer for camping. Nice old non-LED bulbs, so no worries about load resistors etc. However... Connected via a small 7 pin to large 7 pin adaptor, the trailer lights seem to be working on a weird diagonal: indicator on the RHS, with the trailer symbol on the dash flashing, and brake light on the other (LHS), but the LHS indicator doesn't work, and the RHS brake light doesn't work.

I've checked the bulbs - all look functional, so its not them. I've pulled the end caps off the trailer frame, and dug out 15 years of mud wasp homes - the wiring all looks sound.

Connectors seem good, all tested, WD40 etc.

I have a memory that this may be down to the euro wiring of the large round 7 pin (12s?) not being Aus trailer wiring compatible - am I right? I suspect the easiest answer may be to rip the large round out and replace with a 7 pin flat/anderson combo.

Questions:

1. Is my assumption re the wiring right, before I return to the trailer... If not, any other ideas?
2. Does anyone have a picture of their 7 pin installation where the black round is? Just want a feel for how easy or not this is to do, and any comments from those who have 'lived experience'(!)
3. Does this cause any reverse sensor/trailer issues?

Thanks for all comments, and if you say 'go to this particular thread you bloody idiot', I will still take that as a win - buggered if I can find it.

[Xtreme]

This link Australian Trailer Plug and Socket Wiring Diagrams | Trailers R Us Australia (https://www.trailersrus.com.au/guides/technical-guides/australian-trailer-plug-and-socket-wiring-diagrams/) gives the standard wiring for various plugs/sockets.
If you have a multimeter or even just a test light you could check the socket on your D4 to determine if it's wired to Aus standards.
HTH

[Briar]

Hi folks, and my apologies - I'm sure this has been covered somewhere else, but I'm without my reading glasses atm, and have given myself a headache trying to find a relevant thread...(is it me, or has the search function just changed? - I'm finding it much less intuitive...) So an ageing bloke would welcome advice on the following:

1. 2016 MY D4, with an untouched factory rear socket setup.

2. Just purchased a second hand trailer for camping. Nice old non-LED bulbs, so no worries about load resistors etc. However... Connected via a small 7 pin to large 7 pin adaptor, the trailer lights seem to be working on a weird diagonal: indicator on the RHS, with the trailer symbol on the dash flashing, and brake light on the other (LHS), but the LHS indicator doesn't work, and the RHS brake light doesn't work.

I've checked the bulbs - all look functional, so its not them. I've pulled the end caps off the trailer frame, and dug out 15 years of mud wasp homes - the wiring all looks sound.

Connectors seem good, all tested, WD40 etc.

I have a memory that this may be down to the euro wiring of the large round 7 pin (12s?) not being Aus trailer wiring compatible - am I right? I suspect the easiest answer may be to rip the large round out and replace with a 7 pin flat/anderson combo.

Questions:

1. Is my assumption re the wiring right, before I return to the trailer... If not, any other ideas?
2. Does anyone have a picture of their 7 pin installation where the black round is? Just want a feel for how easy or not this is to do, and any comments from those who have 'lived experience'(!)
3. Does this cause any reverse sensor/trailer issues?

Thanks for all comments, and if you say 'go to this particular thread you bloody idiot', I will still take that as a win - buggered if I can find it.

When I got my D4 in 2014, I knocked up this diagram for my Auto electrician to make sure he knew "what was what". The only thing he had to do was pull off the 12N socket and re-wire pin 5 to be the Service Brakes rather than RHS tail-lamps which is the default for pin 5 on the 12N.Pin 2 is not used. I got the sparky to wire up my 12 pin flat plug for the van with the appropriate pins from the 12N and 12S to be correct for my vans configuration needs. In this way I use the 12 pin flat for van, but just use the 12N with appropriate adapter when towing any trailer.
I would suspect your 12N is wired as either original factory setup or for Australian standard by modifying Pin 5. It's probably the trailer. Use a multimeter to check each pin.

180771180772180773

[trout1105]

I had the same problem on a boat trailer once.
After replacing the trailer plug and the tail lights it still didnt work properly, only one indicator and brake lights working.
It turned out to be the wire from the plug to the tail lights was old and broken and had to be replaced.
Once I replaced the trailer cable everything worked perfectly.

IF your plugs are wired up correctly and the lights are in good working condition it Has to be the cable itself that is the problem which is a pretty cheap fix[thumbsupbig]

[Jpdv]

It turned out to be the wire from the plug to the tail lights was old and broken and had to be replaced.

That is actually my first assumption, but I just wanted to check that there's not some LR weirdness that I should be aware of, as there so often is(!).

[BradC]

the LHS indicator doesn't work, and the RHS brake light doesn't work.

There's your answer. That is not possible if the trailer is wired and functioning correctly. There is only one brake light output from the car, so if they both don't come on simultaneously it can't be the cars fault.

[BMKal]

I recently scored a second hand trailer when my son moved over east and left his old trailer behind. The lights and wiring were in pretty sad state, so I replaced the lot. I simply wired it as per Australian standard trailer wiring diagram, using a large, round 7 pin plug - and everything worked as it should. Both my trailers are fitted with the same plug - the only modification I have made to them is to include load resistors on the indicator circuits, as they are both running LED tail lights.

Given that you have purchased a "second hand" trailer - my first course of action would be to throw out whatever plug is on it and replace it with one that plugs directly to your D4 without any requirement for an adaptor. Use a multimeter or test light to check that the pins on your D4 are as per Australian standard, and wire the trailer up to match. An easy way to determine which wire on the trailer does what is to put a small car or motorbike battery near the tow hitch - connect the earth wire from the trailer to the negative post (or if you don't know which wire is the earth, just run a separate wire from the negative post of the battery to the chassis of the trailer and make sure you get a good connection). Then individually connect each of the other trailer wires to the positive terminal of the battery and visually check which light has illuminated on the back of the trailer. Label each wire as you determine what it is, or connect it immediately to the appropriate pin on your new 7 pin connector. Once you have identified and labelled or connected all wires - the one left that did nothing is your earth wire.

[BradC]

connect the earth wire from the trailer to the negative post (or if you don't know which wire is the earth, just run a separate wire from the negative post of the battery to the chassis of the trailer and make sure you get a good connection). Then individually connect each of the other trailer wires to the positive terminal of the battery and visually check which light has illuminated on the back of the trailer. Label each wire as you determine what it is, or connect it immediately to the appropriate pin on your new 7 pin connector. Once you have identified and labelled or connected all wires - the one left that did nothing is your earth wire.

If you do it that way, the earth will be the wire that emits smoke when you put it on the positive terminal. If you put a 21W bulb between the battery negative post and chassis, all will work the same, but the bulb will light up brightly when you find the negative wire.

[BMKal]

If you do it that way, the earth will be the wire that emits smoke when you put it on the positive terminal. If you put a 21W bulb between the battery negative post and chassis, all will work the same, but the bulb will light up brightly when you find the negative wire.

Well that's a quick and easy way to find the earth wire. [bigwhistle]

[johnp38]

If you do it that way, the earth will be the wire that emits smoke when you put it on the positive terminal. If you put a 21W bulb between the battery negative post and chassis, all will work the same, but the bulb will light up brightly when you find the negative wire.

Just to add a bit more detail , the bulb between chassis and negative post will light up every time one of the trailer lights works and both will be duller than normal due to the 12v being shared across the trailer bulb and chassis bulb, then when 12v is put to the earth wire of the trailer plug the chassis bulb will be its brightest and no trailer bulb will be lit.

[Jpdv]

Soooo....

1. Replaced all trailer wiring. All now new and shiny.

2. Used multimeter, verified that the factory plug is wired correctly for Aus 7 pin.

3. Swapped bulbs in and out.

4. Result: Disco is seeing trailer, both indicators work, with dash trailer symbol. Check. Lower bulbs work as tail lights when I turn on Disco lights. Check.

5. Both lower bulbs stubbornly refuse to work when brakes are pressed. (and multimeter shows 12V on pin 6 at this point...).

Anyone got any ideas? I'm going to swap out both of the brake globes again, but they look fine to the naked eye. The wiring is all good, so I'm running out of ideas...

[BMKal]

180973

If you are getting 12V at pin #6 when you push your foot on the brake pedal, then the problem MUST be in the trailer wiring.

Check if you are getting 12V at the contact point/s for the brake light globes at the back of the trailer. Check also that you have a decent earth connection from the body of the globe to the trailer and/or earth wire back to pin #3 on the trailer plug (I'm assuming that if these same globes are working OK as "parking" or "tail" lights - the earth connection should be OK).

Assuming that we are talking about conventional dual filament globes as shown below -

180980

there will be two "contacts" in the base of the socket for each globe. One "contact" should show 12V when the parkers / tail lights are turned on, the other should show 12V when the brakes are activated. Earth for both circuits is common and through the side / body of the globe fitting.

[BradC]

You've used "lower bulbs" twice, in the context of tail lights and brake lights. From that I *assume* that you've used dual filament 5/21W bulbs.

There are a number of issues that may be at play with the trailer wiring, but we've not got a lot to go on. Have you scratched out a diagram complete with colours and pin numbers?

[trout1105]

Why are you still using globes when LED trailer lights are as cheap as chips these days.?
LED trailer lights are far more reliable than the old school globe jobbies and they are waterproof to boot [thumbsupbig]

[Jpdv]

In no particular order,

1. I'm still using globes in this instance because it came with them, and it avoids playing with resistors to let the D4 'see' the trailer.

2. Thanks for all the help. In the end it turned out to be 3 separate issues:

The original socket at the front was shot. Replaced it and all the wiring.
The LHS light unit had a weakened/misaligned terminal: the arrow is pointing at it.
180983

This, irritatingly, didn't become obvious until issue 3 was identified - the bulb there was dead on the brake circuit... Once I swapped the globes, this became obvious.

All good learning, and the multimeter proved its worth about 12 times. That said, before I worked out the dodgy terminal, it was spooky to be getting a reading of 12V from the multimeter there (because I was pressing into both terminals), but then not getting a known good bulb to light up!

In closing, on my own today, so here's the assistant brake pedal operator...

180984

worked very well if anyone ever needs to do the same.

(and I'll go LED in due course, just not wasting the supplied bits in the first instance...)