And also some aftermarket turn signal switches do have a ground wire. Mine does and the poster is installing a non-original device, so I can't say whether it does or doesn't. If you happen to have a model like one of the Grotes with right/left blinker bulbs and an emergency flasher bulb built into the unit none of those bulbs will work without ground. In the model I have, if any bulb fails to work or if it loses ground all the bulbs in that chain won't flash until the problem is solved. The instructions were clear on this point, also.
