Unhelpfully, the wires aren't that different in thickness, which doesn't help either.
[quote="shrig1969"]1+2 are the red/black connections back to the din[/quote] what do you mean by din ?. The cable there is typical 2 core aftermarket cable, let's work through what is there, and imagine the base of the relay is a clock:
Terminal 1, coil feed, 9 o'clock - Is this the 12v feed from fuse 12, green wire
Terminal 2, coil earth, 3 o'clock - there should simply be a short wire to the chassis to complete the coil circuit. Is this earth hidden by the relay case in the second photo, black wire
Terminal 3, battery feed, 12 o'clock - missing
Terminal 5, feed to fridge, 6 o'clock - red wire in the 2 core cable
Black wire in the 2 core cable should be the -ve or earth cable from the fridge, connected to the same earthing point as the relay coil ?
Can you check the assumptions above with the van. If all is correct, then you do just need a fused 12v feed from the battery. If the fridge has a warning light and you want to see if it illuminates before ordering parts then simply run a temporary wire from the battery and hold it against terminal 3 for a second or two. The fridge light should light up if the engine is running.
