Hello ,
I have no idea which wire is hot wire and which is ground , can anyone tell me how I can find that out ?
I have a multimeter if it´s needed.
Pickup : https://ibb.co/D786g9f
multimeter : https://ibb.co/M2GJ6p3
Are you using more than one? If so do they have the same wires? If either answer is "yes" it may not matter. Just treat one wire as "hot" and the other as ground. If using more than one pickup, just make sure the wire you use as hot is the same color for both. I think with a lot of PB kits the red/yellow wire is intended to be hot.
I don't see shielding on yours. That would be like a silver colored mesh between the insulation and the two wires from the pickups. That would need to be grounded.
Pickups don't have a ground, per se, unless they have shielding. They have polarity, a north and a south. As long as you treat the N and S on one pickup the way you treat it on the other, you should be fine.
The exception to this would be if the shielding mesh is connected to one of the wires. Since the black one is fatter, I'd probably treat that as the ground...but without seeing the bottom of the pickup it looks like these pickups don't have shielding around the pickup wires so it probably doesn't matter.
The red wire is ‘hot’, the black wire is ground. The black ‘wire’ is in fact the braided shielding that’s been rolled up and covered in heat shrink, which is why it’s thicker. If you want to double check with a multimeter, the end of the black wire should be connected to the pickup base plate.