Thread: Problem with trailer plug electrics

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.

Originally Posted by 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

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.

Originally Posted by 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.

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

Originally Posted by SeanC

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.

Originally Posted by Odysseyman

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 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.

Originally Posted by DieselLSE

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 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?

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.

Originally Posted by 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.

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!!