I did this on 2006 drz 400s. If you remove the light cover you will see a plug with six wires on it. The wire you tap into is the solid orange on the corner of the plug. On my unit there was a whole on the ignition switch and a toggle switch fits perfect with no modifications. I recommend splicing the orange on the handle bar switch side... this side can be easier replaced and there is more room for splicing. I did this so my bike would start better..... And sometimes i like to go unnoticed. The 6 pin block goes to the right handle bar. They bring the headlight wire up to the starter switch so when you his the starter it kills the headlight. But this is also the location where the taillights gets it power so if you switch the orange all the lights go out.