I'm thinking of adding DRLs to my car. I've seen people suggesting that a good power supply for them is a blue and white wire on the wiper motor. I've already got a normally-on relay that I can wire to the blue/white wire for a power supply and I can wire the other terminal to the regular lights to switch off the DRLs when the main lights are on. However, I have some questions:
Normally, if I am wiring additional components (fog lamps, driving lamps, etc) I would expect to use a normally-off relay. I would take a power feed from somewhere like the regular lighting circuit to switch the relay on and then a completely new power supply (that gets switched on by the relay) to actually supply power to the new accessory. i.e. the only additional load on the existing circuit is the current needed to switch the relay and the power for the accessory itself would come from its own supply.
DRLs are a bit different because they are always on by default. It also seems that most people just put an inline fuse into the wire that they splice to the blue/white wiper motor wire and then use it as the main power supply for the DRLs. This obviously puts additional load on the existing circuit. My main question is, is this OK? My guess is that LED DRLs don't draw much power so the additional load on the circuit is negligible?
In addition, I'm interested in what the blue/white source wire is for. I assume that it's a power supply of some sort for the wiper motor but I'd also like to know which fuse it is connected to in the car fuse box (just in case things mess up and I blow a fuse).
If anyone can help with the above it would be greatly appreciated. Thanks.