Towbar electrics used to work fine (2 years ago) but on testing with two different trailer setups today .. nothing.
Went right back to the Trailer Control Unit (the box behind the trim) that takes CANBUS in and then drives the appropriate connections down to the trailer socket.

Question: Does anybody know what lights/connections on the trailer it needs sense before it starts working?
It certainly doesn't see the trailer lights as connected (no indicator failure tell tail on the dash, or disabling reversing sensors)

So my guess is that unless the Control Unit senses a trailer connected it Doesn't drive power to the trailer lights. SInce none are currently being driven .. but the 12v supply in is good. hence the question

If for some reason the ECU was re-programmed (I've had a couple of SW updates since I last used the towbar) without the trailer option, would any of the trailer lights work?

Thks

Andy

I believe unless others can offer a bit more that you will have power to the lights socket etc at all times even if it has not had the unit activated, when you then plug the trailer plug in activation then turns off the Rear Parking Sensors, Rear Fog Lights and the Trailer Indicator on the Dash will the flash withe the indicators along. So you may have a problem with the Module itself

AndyP wrote:

Question: Does anybody know what lights/connections on the trailer it needs sense before it starts working?

AndyP wrote:

If for some reason the ECU was re-programmed (I've had a couple of SW updates since I last used the towbar) without the trailer option, would any of the trailer lights work?

Update, my local 4x4 garage plugged in their CANBUS monitor .. the Trailer COntrol Module is configured.
However with their led based trailer plug tester we could see all the leds flash when the ignition is turned on.
Looks like the Trailer Control Module has failed since when you look at the outputs with an oscilloscope there is about a 1/2 sec on - off cycle on all outputs where the voltage swing is only 5v .. hence it must be some sort of failure in the module ... now the challenge is to find a module without purchasing the whole kit!

There has been a LR Special Service Message about towing electric modules:

Quote:

Reference SSM45936
Models Freelander 2
Title L359 – Freelander 2 Towing Module
Category Accessories
Last modified 04-Nov-2010 00:00:00
Symptom Electrical Accessories
Content
Issue:
Customer may report either failure of Trailer Lights or inoperative PDC

Cause:
Towing module out of communication with vehicle

Action:
Before replacing the module try to re-configure the unit with IDS. This can take a few attempts before communication with the vehicle is gained. Check to see if all towing electrics and PDC are working.

Thanks ...

I'll update when it's been reset.

Andy

Update

snapper got it spot on ... the trailer module needed to be re-configured

Of course the question is .. how did the trailer module lose its brain in the 1st place since it was working just fine (admittely it's been a couple of years since I last connected a bike rack )

The 5v swing is some sort of detection routine by the controlling FETs , once you connect a 'bulb' type resistance in-circuit they detects it just fine. This occurs before (and after) the unit got re-configured.

Oh for the days of connecting trailer socket via those funky piggy back scotch connectors.

Andy

I have been told by the company that makes/sells the module "Land Rover have a sequence for trailer recognition, which is any time the trailer is installed or disconnected the ignition needs to be cycled and the brake touched".
Have yet to test this method, but when my module does not work, eventually by switching on side lights, hazard flashers ignition the unit bursts into life, so I may have stumbled across the solution, but as I can't remember the exact sequence, I will try this method next time I have problems.