An overhead light controlled by two switches won't light. The other fixtures/receptacles on this circuit work.

Is there a "most likely" candidate for what is wrong? I think I understand the steps needed to eventually track this down, but it would be nice to start at the point of highest probability.

First I'd check the bulb or fixture. If the light doesn't work, how do you know it's the same circuit? I've seen people spend a lot of time to find out a wire at the fixture is burned off. If not the bulb, pull the switches out, look for loose or corroded wires, particularly if they are back wired-pushed in. Depending on how the switches are wired, you could have hot through the switch or a switch loop so be careful with testing continuity by an ohm meter. Use voltage checks first.

The bulbs are okay.

I'll start with the fixture.

I wired the circuit 16 years ago so I know which breaker it is on. Don't think I used the push in, but...

Could be a bad switch, are they 16 yrs old also? 3 ways are a bit more problematic since there are 2 sets of contacts to pit or burn out.

Yes, everything is 16 years old.

Okay, fixture first, then switches.

This is the first failure I've had in any of the work I've done over a 25+ year period.

Thanks!

I wouldn't call this a failure by any means. 16 years is a long life for a ceiling fixture wiring or a switch. Congratulations! Brian

How embarrassing.

One of the switches had a backed-out wire. Fortunately, there was enough wire in both boxes to fix all the connections.

I guess I did this before back stabbing was known (to me) to be bad.

Thanks for the help.

The connection called back-stabbing, Whiz Wire, Quick Wire, etc, is the absolute worst connection method I have come across.

Good for producing service calls and making money, frustrating when a simple problem causes a circuit to not operate, and need to find that connection.

These loose connections often damage the device it was plugged into, not so much switches since the load is low, usually receptacles get damaged from heat due to the higher loads and usage.

Well done.