Rear PDC/OPS defaults to tow hitch

[John A]

Hello,
I've had a cursory search through some of the forums and can't find the answer I'm looking for - similar, but not quite the same.

Our T6 has factory OPS (as I assume all Highlines do) and has a Westfalia detachable tow hitch.
We bought the van last March and the tow hitch has never been removed. It all functioned as normal until I towed a car on a trailer for a couple of days at the end of January this year. Ever since then, by default, the OPS shows the trailer as connected and deactivates the sensors, unless you press the brake (which obviously triggers a voltage).

Has anybody encountered this before? I don't think VCDS is highlighting anything, but I should probably check again.

 

[F-roger]

There is a small limit switch in the outlet where you connect the trailer's electrical equipment. You haven't used the trailer for a long time and this switch is stuck! Just clean the outlet well

 

[John A]

Thanks
I did get down underneath the van the other evening and pressed the switch in and out in the hope that it might release, but no luck so I think I am going to have to disassemble it and get the contact cleaner out.

 

[John A]

As I don't own a trailer or anything to tow (I borrowed the trailer to tow the cars), I bought a 13 pin plug and some specific contact cleaner (don't know why I bothered, as I buy IPA by the gallon), with the intention of spraying the connector with contact cleaner and connecting the plug until the switch released.

Only, after 6 and a bit months, the problem looked like it had righted itself

 

[John A]

The problem hadn't righted itself at all
It's also not got 13 pin electrics...
I spent some time on the floor with the contact cleaner and a screwdriver to press the switch in. I am not sure the switch does anything other than indicate to the electrics to deactivate the rear fog light.

I have also tried to source a replacement Brink branded 7 pin socket, but after writing to Brink directly, the message I got back was "well it depends what brand you've got"
BRINK - IT SAYS BLOODY BRINK ON THE FLAP
That's Nuneaton people for you

Anyway does anybody know where the trailer electrics modules are? I thought it was wired to the battery in the engine bay, but that's something else with "Cobra" branding on it. It can't be an additional alarm surely

 

[Deaky]

If it's a factory installed tow bar then the trailer module is under the drivers seat

 

[John A]

So....
It's not a factory installed module - it's a Brink-supplied Jaeger module and has been coded as factory, I assume to make the OPS display on the head unit work.

I went to see a towbar guy on Saturday (really good - highly recommend Andy at towbarsuknorthampton.co.uk) who took a look at the system, plugged his test kit into it and decided that it's probably been wired up wrong, particularly the switch. He kindly gave me a new 7 pin socket to replace the Brink one - he did say the Brink wiring would probably have its own bespoke connectors, so a new Brink plug would be plug and play but as they are difficult to get anything out of, I will cut all the connectors off and wire in the new one and hopefully problem solved.
If not I'll need another plug with a switch in it.

 

[John A]

I took the old Brink socket off and found it was all screw terminals, but I did find the wiring colours were all different (not a big deal as I managed to pickup a wiring diagram).
I cut all the knackered ends off each wire and crimped on a ferrule just because I wanted to have a go with my ferrule crimper...

Now, there are 8 connections which included the one to the switch. The old Brink plug looked like the switch contact had bent and was permanently open (which I thought would have been the culprit). I fitted the 7 pin socket leaving the fog cutout disconnected, put it back together and ordered a replacement 8-pin (with switch) socket.

I've fitted this but am still getting the bloody display that shows the trailer electrics are connected, until I put my foot on the brake and open the circuit.
I went out in the dark on Monday and it seemed to be ok - I assumed because the taillights were on - but at my third start of the engine (running errands) and engaged reverse, I was back to the same problem, so it's almost intermittent. I also now wonder if it is drawing current when not running as the radio display showed "12v battery almost flat, radio will switch off" or whatever it says, and the van was sluggish to start. I have RAC battery cover, so am not overly concerned about that and the battery is probably 8 years old.

But what could be causing it? A knackered module?
I've contemplated coding it out because it's not really used at all.