Problem with trailer plug electrics

[Odysseyman]

On Thursday last week went to pick up our new to us, 1 year old, Titanium caravan. Until recently we have been towing another brand and the trailer plug connections were working as they should. On arriving to pick up the new van we plugged it in as usual and found we had no clearance and taillights and also no trailer brakes.

In preparing for the new van I had to change pin 9 to pin 11 in the 12 pin plug and while there I checked and tidied up all the 7 pin connectors. These are all connected properly however I have no power to pins 5 blue (electric brakes) and pin 7 (tail and clearance lights). My stop lights and indicators all work as they should.

My challenge is now where to look in the car to try and find the issue and fix it.
As I need to take the van to VicRoads for an inspection to have it registered in Victoria (it’s currently Qld) I need to sort this very quickly.

So far I have had the some incredible service from Titanium. I phoned them on Friday and spoke to their electrician and he offered to come to my home, over an hours drive from his place, which he did yesterday. He checked every fuse in the car, both under the bonnet and in the passenger compartment, checked the wiring to the van from the car and then tried to trace the loom back into the car behind the left hand taillight. He did find what he thought was a broken brown wire however, on reading through sneigys post from years ago (I’ll post up a link to that later) about how to wire in a brake controller, it seems this wire is one that is cut and not used in the installation process.

Here I need to give a big shout out to Titanium. Their service goes over and above all expectations. What a fabulous company to deal with.

The car is fitted with a Redarc Tow Pro Elite and I have been towing 2 vans with it all for the last 6 years without any issue.

So can anyone help please, it would be much appreciated.

David

[DieselLSE]

Just to clarify: do your trailer indicators work and does the car recognise the trailer is attached? The Tow Pro controller will not power up if the trailer is not recognised.

[SeanC]

On Thursday last week went to pick up our new to us, 1 year old, Titanium caravan. Until recently we have been towing another brand and the trailer plug connections were working as they should. On arriving to pick up the new van we plugged it in as usual and found we had no clearance and taillights and also no trailer brakes.

In preparing for the new van I had to change pin 9 to pin 11 in the 12 pin plug and while there I checked and tidied up all the 7 pin connectors. These are all connected properly however I have no power to pins 5 blue (electric brakes) and pin 7 (tail and clearance lights). My stop lights and indicators all work as they should.

My challenge is now where to look in the car to try and find the issue and fix it.
As I need to take the van to VicRoads for an inspection to have it registered in Victoria (it’s currently Qld) I need to sort this very quickly.

So far I have had the some incredible service from Titanium. I phoned them on Friday and spoke to their electrician and he offered to come to my home, over an hours drive from his place, which he did yesterday. He checked every fuse in the car, both under the bonnet and in the passenger compartment, checked the wiring to the van from the car and then tried to trace the loom back into the car behind the left hand taillight. He did find what he thought was a broken brown wire however, on reading through sneigys post from years ago (I’ll post up a link to that later) about how to wire in a brake controller, it seems this wire is one that is cut and not used in the installation process.

Here I need to give a big shout out to Titanium. Their service goes over and above all expectations. What a fabulous company to deal with.

The car is fitted with a Redarc Tow Pro Elite and I have been towing 2 vans with it all for the last 6 years without any issue.

So can anyone help please, it would be much appreciated.

David

I’m not sure it’s the same problem. My American boat trailer came with a flat 12 pin connector. I was told a 7 pin flat to a 7 pin round would work. My trailer brakes didn’t work. I wasn’t getting power to the trailer brakes. The auto electrician picked up the power wires from the trailer loom and added an anderson plug which connected to the anderson plug I have underneath the rear bumper. Fixed the problem.

[Odysseyman]

Just to clarify: do your trailer indicators work and does the car recognise the trailer is attached? The Tow Pro controller will not power up if the trailer is not recognised.

Yes, the trailer indicators work however I don’t see the trailer light on the dash…

[Odysseyman]

I’m not sure it’s the same problem. My American boat trailer came with a flat 12 pin connector. I was told a 7 pin flat to a 7 pin round would work. My trailer brakes didn’t work. I wasn’t getting power to the trailer brakes. The auto electrician picked up the power wires from the trailer loom and added an anderson plug which connected to the anderson plug I have underneath the rear bumper. Fixed the problem.

on my AOR camper it had ALKO disc brakes which needed a separate Anderson plug supply from the starter battery to power its compressor. The brakes on the Titanium are the Cruisemaster supplied discs and are powered from the house batteries. Hope this addresses your thoughts.

[DieselLSE]

Yes, the trailer indicators work however I don’t see the trailer light on the dash…
Then the trailer is not being recognised. Your car is checking for resistance from the trailer indicator bulbs which it assumes are 21w incandescent. But they're LED. It is a simple matter of putting resistors into the circuit. Easiest way is to modify the trailer connectors. More tricky is modifying the car's wiring. Have a look here Discovery 3 LED trailer lights (https://www.aulro.com/afvb/the-d3-d4-sticky-zone/85396-discovery-3-led-trailer-lights.html) towards the later posts that cover the D4 which is a little bit different.

I have one I made up here you can borrow. It's a bit crude but works OK. The whole thing is mounted to an old computer heat sink and the resistors are mounted externally.

[Odysseyman]

Then the trailer is not being recognised. Your car is checking for resistance from the trailer indicator bulbs which it assumes are 21w incandescent. But they're LED. It is a simple matter of putting resistors into the circuit. Easiest way is to modify the trailer connectors. More tricky is modifying the car's wiring. Have a look here Discovery 3 LED trailer lights (https://www.aulro.com/afvb/the-d3-d4-sticky-zone/85396-discovery-3-led-trailer-lights.html) towards the later posts that cover the D4 which is a little bit different.

I have one I made up here you can borrow. It's a bit crude but works OK. The whole thing is mounted to an old computer heat sink and the resistors are mounted externally.


Sorry, I’m a bit confused…

The indicators all work perfectly on both the car and the trailer but I am not getting power to the taillights and clearance lights on the van, nor are the electrically operated disc brakes working (getting power).

My previous camper had LED taillights and everything worked as it should.

Are you saying that I now need to fit that resistor regardless. Sorry, I wish I understood this better.

Is there anything else in the car or wiring that could affect this? Could it be the Tow Pro brake controller playing up?

[DieselLSE]

Again, just to clarify. Does the trailer symbol on the dash light up in time with the dash turn indicators? If yes, then the car recognises the trailer. If not, then it doesn't.
My Tow Pro Elite only activates when the trailer is attached. I forget how it picks up the signal.

[Odysseyman]

Again, just to clarify. Does the trailer symbol on the dash light up in time with the dash turn indicators? If yes, then the car recognises the trailer. If not, then it doesn't.
My Tow Pro Elite only activates when the trailer is attached. I forget how it picks up the signal.

Okay, then it doesn’t recognise the trailer. Would that then be why there’s no power to the brakes?

I’m beginning to suspect the Tow Pro. I have just finished inspecting and reconnecting all the wiring in the back of the car however the Tow Pro still isn’t lit up. Stop lights and indicators work on the caravan but still nothing to the brakes or clearance lights. Aaaaaarghhh!!

[DieselLSE]

Would that then be why there’s no power to the brakes?

Yes


I’m beginning to suspect the Tow Pro.

I doubt it

[DieselLSE]

This may help.

[rocket rod]

If you are getting some lights on the trailer working but not others then it's either the lights themselves (all of them faulty at once is very unlikely) or the wiring. Check every pin on the car trailer plugs to see if they work as they should with a multimeter. If not, then you've isolated the problem to the car harness setup. If it's ok then move onto the trailer wiring and do the same proceedure. My money is on a loose wire or corroded pins in the car plug.

[Odysseyman]

If you are getting some lights on the trailer working but not others then it's either the lights themselves (all of them faulty at once is very unlikely) or the wiring. Check every pin on the car trailer plugs to see if they work as they should with a multimeter. If not, then you've isolated the problem to the car harness setup. If it's ok then move onto the trailer wiring and do the same proceedure. My money is on a loose wire or corroded pins in the car plug.

Thanks for the thoughts but no loose wires, no corroded pins - all checked very thoroughly by an auto electrician on Saturday. Unfortunately he had limited time to look further AND it was ****ing down with rain. He also checked both sides of every fuse in the car and had a good look at the way the loom was wired.
I’m going to look for broken wires through the week.
I’ll report back with what I find.

[V8Ian]

Prioritise getting the car to see the trailer, ie the trailer icon to illuminate with the blinkers.

[Tombie]

We are lookiing at 2 seperate issues here.

Vehicle not recognising trailer is plugged in is a LED light issue. It wont be causing the other issues.


The second problem is the one to focus on - no tail or brakes...

Start by getting a multimeter and probing the trailer plug.

[Odysseyman]

Well, have solved the problem. Whoever originally wired the car completely messed up matching the wire colours. Swapping a few around has resolved the issue.
thanks for all the advice. It was just a process of doing things one by one.

[TonyC]

Thanks for the thoughts but no loose wires, no corroded pins - all checked very thoroughly by an auto electrician on Saturday. Unfortunately he had limited time to look further AND it was ****ing down with rain. He also checked both sides of every fuse in the car and had a good look at the way the loom was wired.
I’m going to look for broken wires through the week.
I’ll report back with what I find.


Well, have solved the problem. Whoever originally wired the car completely messed up matching the wire colours. Swapping a few around has resolved the issue.
thanks for all the advice. It was just a process of doing things one by one.

Presumably not checked that thoroughly by the auto electrician 🥺

Glad you've got it sorted.

[Odysseyman]

Presumably not checked that thoroughly by the auto electrician 🥺

Glad you've got it sorted.

Yes, a complete mystery! I still can’t fathom how my past two campers worked perfectly, both had been wired according to the Narva plug colour specs, but my new van is working perfectly after a two day shakedown so I’ll leave it alone and not overthink it.