Caravan fridge not working on car electrics

19Gra40
19Gra40 Forum Participant Posts: 49
edited June 2014 in Towcars & Towing #1

I have a VW Tiguan sept 13. Had tow bar fitted by specialist I have used before on previous cars. Problem is fridge in caravan not workind whilst travelling(found this out by chance probably hasnt worked since I have had it)When I hitch up and start engine
all OK. After driving 1hr and with engine still running , entered van and battery ico  flashing, telling me either low or no voltage, no matter what I did turn engine off and on again made no difference. Arrived at site stayed a few days , set off again ,
all OK drove for 1hr , same again battery icon flashing.Is it caused by low voltage between car and combi relay or between relay and van. Dometic say should be 6mm cable between car and van, tow bar people say not needed,  they use a smaller size.. Hope you
understand this!! any ideas please.