I have tested both options, the one with the switch on the fuse box works but on my 2018 1500 denali not only disable the stabilitrak and traction control but also disables the power steering pump, so the steering will be heavy. on the toggle with the harness on the driver side ABS harness with the switch works better because it interrupts the signal telling the computer that the ABS is not working, so in theory the stabilitrack and traction control will not work and the light on the dash will come on until you flip the switch back.