I changed my brake lights yesterday and they worked. Slapped the new ones on and tested the lead and now im only pulling .5v. Think its a ground or regulator issue? Ideas?
1987 Sportster

 

Check the voltage at the connector at the taillight. If there is 12 volts there it is most likely the ground or the bulb is not making good contact with the holder. If the voltage is low at the connector then there is a bad connection further up stream, check voltage at connectors upstream until you find the problem.

Good luck

 

That's gonna suck... So you don't think its a regulator issue?