Accessory wiring

[judoant]

I am in the processes of some rock light wiring and plan to make my own harness. I have a question though and I have found conflicting information.

Does the power for the switch need to be fused separately from the power for the lights? I want the ability to opperate the lights with the truck off so I plan to draw power for the switch directly from the battery.

The top attached diagram show a 3 amp fuse for the switch and a 20 amp fuse for the lights. I know the lights will not need that large of a fuse.

The bottom picture and the harness I currently have for my LED bar only has 1 fuse.

 

[Wraytex]

I would fuse the switch/relay circuit separate with a low value fuse as it is a separate circuit that could have a relay coil defect such as shorted internally. Just run both circuits off a constant hot that has the capacity for your amp draw and you should be fine. Is your switch lighted? When i got my 2000, there were two aux lighting circuits powered direct from the battery and the led's on the switches themselves ran 24/7. I rewired them to an accessory hot so they wouldn't run all the time. Which I know is opposite what you are trying to do here.

 

[TheDurk]

The lower circuit only has one fuse, because the fuse is upstream from both the switch and the load. One fuse covers both circuits.

The upper has a separate fuse, which is sort of belt and suspenders. If the tap is on a vehicle circuit that is fused, it is optional. I don't fuse switches which are tapped to fused circuits, but in theory, the low value fuse provides a more precise level of protection. If it's pre-wired into a harness, use it.