So my 68 stopped being able to start the other day. I removed the battery and alternator and had them tested since I just installed a new starter motor a couple months ago. Both battery and alt came back bad. So I install a new voltage regulator, new alternator and new batt, in that order. The car fired right up, almost impatiently. Now I have no headlights. Everything was working fine before she quit on me and now with the new installs the headlights don't work, but everything else does. The front right parking light is out since I'm waiting on a new socket for it but I thought that should be a separate issue. I'm assuming a bad ground somewhere but with old wiring, I have no idea where to start. Why would a new volt reg affect the headlights only? Also I noticed the fuel gauge dropped from F to about 1/3 while I was messing with the lights. I have no idea what all this has to do with each other. If anyone has any input or experience with buggy circuits I'd be eternally grateful. I have to drive to night class and I'm just begging for a cop to notice me driving with only one parking light.

 

I suspect you may have had a short in the light circuits killing the battery, and not the other way around. The alternator may also have died of overwork. You will need wiring diagrams for you car to get to the bottom of your problem.

 

It sounds to me like the ground may have broke/disconnected when you were in doing your replacements. I've attached a diagram to help you trace out other wires in case the ground isn't it. Good luck!

 

Recheck all your connections also, may have loosened headlight relay when you changed other stuff