Hi Prm,
Your making progress with your electrical problems.
You had me going, as I was thinking, there could not possibly be that big a change in the electrics between my 2013 and your 2014 van... could there ! (then again this is Jayco ). My mate had a 17.56.2 and it was wired the same as mine.
So I went and got my Jayco Manual.. The 12 Pin Electrical plug break out in the manual is detailing the industry standard .. does not mean Jayco actually followed it.. I know confusing..(you find the same info on the back of a Navara trailer plug packet)
Pin 2 is the industry standard for Reverse signal.. there is no reverse lights on a Jayco van.. so on my van (straight from the factory ) they put the Battery charging wire, a thick black wire (why use pin 2, I have no idea). Tow bar installers will still have reverse connected to pin 2 on a Tug, so need to careful with this.
Pin 9 runs my fridge direct wire (through the jungle/jumble as most appropriately named).
(I note a previous post mentions a combined hot-wire splitting to the fridge and Setec. This was the case for my Jayco Swan, but not the Expanda. The 150lt fridge draws approx 15A on its own (fridge manual recommends a 20A fused circuit), hence Jayco put the extra hot-wire in.
13V on Pin 9 on tug is good start, 0.6V at Fridge is bad.. so good find.. now need to know why.
I am sticking to my original thoughts, where is the second hot wire?
My suggestions;
1. With your van battery isolated, tug plugged in, does your internal van lights work.. if yes, then power is from your tug. Pull the trailer plug to double check. (Mine does this). Just checking if this part of your hot-wires is working.
2. I would take the covers off your trailer plug and check you have wires on pin 2 and pin 9.. (and white wires to pin 3 & 10).
Pin 2 on mine was a black wire thicker then the rest of the trailer light wires on the 7 pin side. (These heavy current wires should stand out as much thicker then the rest)
(Like I said before, if you have a wire on your van plug pin 2, then it is for something else other then reverse lights, unless you had a set fitted)
Pin 9 is a very thick pink wire (in the Jungle/jumble this will connect to a Thick red wire with a Wire Joiner and goes to the fridge)
Pin 10 very thick white wire is the fridge earth..(changes to a very thick black wire and goes to the fridge)
Actually this is a good point.. make sure you have a earth on pin 10 on the tug.. otherwise no power at fridge as missing earth return (I think I recall all the earth points are not common on the van, fridge earth is separate to the rest ).
I am also not sure where you earthed the multi-meter when you tested pin 9 on the tug, if you used pin 10 then good.
I hope this helps you, not confuse you.
Sorry for the long response.
Cheers