So I just hooked up an aftermarket tach and I have created a very strange electrical issue. I used the power from the radio since it is hot when the car is on and then grouded it to the same ground as the radio. Well my turn signals both work when the headlights are off. But whenever I turn the headlights on, or even the driving lights, my right turn signal doesnt work. My left still does but the right turn signal turnns on but it does flash just a steady light. So somehow I bypassed the flasher for the right turn signal. How on earth did I do this?! Or is it just a coincidence and its something else. Also whenever I unplug the tail light fuse the right turn signal will flash. I dont understand whats going on. haha

 

sounds like the wire on the radio that you thought was a ground is actually the power for the radio lights when the headlamps are on. this will cause power to back feed and alot of weird problems. remove the tach ground and reground to something metal.

 

first unhook the tac and see if issue returns to normal state, if not it is just coincidence and I'd try replacing the flasher, if that doesn't cure the issue, look for a shorted bulb socket or bulb on that side