My daily driver is a 2006 VW Passat 2.0 TDi estate. It has a towbar fitted with twin (12N/12S) electrics for towing a caravan. I fitted the towbar but had a towbar fitter do the electrics due to the low-current wiring requiring a special relay & probably a whole host of other wizardry that I couldn't do with a roll of insulating tape & a bag of scotch-locks. This was done when the car was new.
I'm collecting a new caravan on Friday which has the new (continental style) 13 pin plug. I bought a 13 pin socket for the car & using a wiring diagram swapped the twin 12N/12S sockets for the new 13 pin socket and.... nothing. All I have got is 12V the ignition controlled pin everything else is dead. I have checked both fuses under the bonnet for the electrics (one for the fridge & one feeding the relay) and both are fine (but I changed them anyway "just in case"). Three of the pins have a permamnent low voltage reading of around 1V.
I have had a look behind the trim panel & all of the wires seem okay, but the relay does smell (like a faint burnt PCB smell). Could this have burnt out, giving the symptoms above (including the low voltage to a few random pins)?