Pin 9

CAN bus

https://en.m.wikipedia.org/wiki/CAN_bus

did you ask for dedicated wiring when they fitted the bar and electrics as if you did then that should have been done automatically, everything working for towing a caravan. did you check that the charging of the caravan battery and the fridge was working when connected to the car.

Hmm! Had the same problem with our Antara, amongst 1,000 other problems with that car. Apparently we only tow caravans 10 miles so we don't need the battery charging or the fridge. That is what the dealer said to me, the tried to charge me another £325 to add the one wire. I did it myself for £2.

Anyway, back to pin 9, that is the direct +12v from the battery. Pin 10 is the caravan fridge. You can test it with a normal voltmeter for voltage, it won't make any difference to the can bus system.

Sadly, some manufacturers don't supply the pin 9 wiring and a separate wire has to be installed, which is a simple job. Why they don't supply that wire is beyond me, and to be honest, if the tow bar fiter didn't fit it, I would go back to them and demnd they fit it.

Thanks lornalou 1 and  Ds3 for your helpful input. Well to be honest I dont renember a conversation as to wether I wanted the loom wired for battery charging or fridge. I assumed that would be a given. We have travelled fairly long distances and frozen items have still been frozen at the end of our journy so I would assume that the fridge is powered. I am going to speak to honda this morning, the tow bar fitting was out sorced ,but If the fitter  hasn't wired up pin nine, after fifteen months I suspect even if he agreed to do it, it would be a rushed job, so I will cut my losses and have it done elsewhere, or do some more research and do it myself.

I`m having problems with my Volvo XC60 (2018) which I can`t get to the bottom of. The ATC powers up following "waking up" the car but each start of the engine (fuel, ferry, breaks etc) with the LED already green results in an interruption to the permanent supply to pin 9 and the ATC self tests again. The fridge defrosts in hot weather on a five hour run though the fridge light is on and no indication for low voltage. 

I have noticed today that the fridge light will come on even with the towing electrics disconnected 

Have you got the main switch turned on, on the PSU.

It isn't an issue, I was just trying to illiterate to  Tigi that lights showing on the fridge may no necessarily mean that it is cooling. Up date on my pin 9 issue. I tested pin 9 ignition off, and pin 10 engine running and got no readings. However when I had a look in the back of the socket both pins were wired up. There are no extra leads connected to the battery. I can only think that the loom came pre wired to the socket, and 9 and ten are not connected through. I spoke to honda, and as I expected they said fridge and power were options and I couldn't have asked for them, but they will look at the parts invoice. After doing a bit of reserch it is obvious that pin 10 has to be wired if you intend wiring pin 9, so I dont think I will tackle it myself. 

Second update. I literally have just been contacted by Honda, and they say that the price I was charged for the towbar indicates that The 12v supply isnt connected they have said that because there may have been some misunderstanding they will retro fit the 12v feed for £95.00 plus VAT. 

Tell them there is no misunderstanding, the European standard 13-pin trailer connector (ISO 11446) is a published standard and applies.

Tell them that it reasonable for you to expect this standard to be followed and that they have no excuse not to expect that you have half a job done. They have the technical capability to fit these circuits so ask them why they do not follow the accepted standard.

Why car companies and aftermarket fitters think its OK to only fit some of the circuits is beyond me. Would it be acceptable to leave the brake lights and turn signal circuits out unless you pay more money?

It has been noted before that Volvo do not seem to understand the meaning of permanent in respect of pin 9, in my view not fit for purpose.