We have two outdoor porch lights on either side of the front door wired to the same switch inside. I replaced both fixtures yesterday...

Previously, the switch only worked with one of the fixtures. The other fixture didn't work at all (no power). After replacing the fixtures, the one that previously didn't work at all now works, but has constant power regardless of the switch position. The other fixture still works just fine, as before.

While installing the fixtures, I noticed the wiring of faulty fixture had the standard black and white wires to hook everything up... while the one that works just fine had two black wires... although it could just be whoever spliced the wires for the outdoor fixtures didn't use the correct colors.

The switch itself is brand new, but regardless, it switches the other light just fine so it is likely not the problem. Not sure if it matters, but the house was built in the 60s and there is no ground wire. Previous owners had limited rewiring done, adding a ground to a few circuits.

So basically, I have two lights that are supposed to switch on/off and only one does. The other has constant power.

 

If this was wired with cable there should have have been a white and black. For the most common wiring for this setup there should have been 2 cables in one of the boxes for a total of 4 wires.. Are you sure there are only two wires in each box? You are not calling a cable* a wire are you? How many cables in the switch box? how is it wired?

*Cable is two or more wires in a plastic or metallic sheath.