Wiring up new push button switches for accessories

Ok I'm trying to hook a 12v outlet in the bed of my truck for a bait tank.. long story I'm also trying to hook a bumper mount light bar. I have 2 new push buttons that match factory ones I've tried just using a add a circuit fuse link and it's making my truck go crazy with just having power on the switches. By just having power on switches my trucks dash had every warning light in instrument panel on and the 4x4. I don't have rear power windows so I put the ad a circuit fuse in that slot. I need power to this 12v hook up with key turned off what can I do to fix this problem? The paper work says I need a diode and a relay because I have a negative switched vehicle. Is there a way around all this?