I just looked up the circuit diagram for a number of dufour models and as i said earlier they are all nearly exactly the same. I looked in forum on this web site for a D310, but could not find the manual for that model.
I have attached a couple of images with the wiring diagram and itemised description of each part. If you look you can see Items A, B, C, K, U, G and Q are all of the relevant parts to controlling the windlass.
Fuse K is sense wire detecting that you engine is running. If Fuse K is OK it senses the engine is running and closes relay C. If Relay C is then closed and Fuse U is Ok it puts 12v to your windlass controller. So check Fuses K and U and if they are OK, check relay C. This all assumes your engine is running
If that’s all good, you will get 12V to the centre pin of the hand controller, which in turn puts 12V to chain up or down on the solenoid item Q
So if Item G is OK (Main windlass solenoid) you can if you are very careful and only for 1 – 2 seconds use a jumper cable to connect centre pin of solenoid (12V supply) to one of the windless motor terminals. If you go up top and take your anchor chain off the gypsy, it then does not matter if you then apply the 12v to anchor up rather than down. If you do it with the anchor and chain in place and you inadvertently connect windlass up, you hard stop again and pop the circuit breaker.
It’s all 12V. So nothing lethal, but if you don’t own a DVM, its one of the best things you can buy for boat electrics
PS If i appear a bit nerdy, its because I’m an engineer, comes in useful owning a boat.