Tail/brake light quit

[Brian VT]

I have a digital multimeter. I set it for resistance and put the 2 probes on the tits of the bulb. It changed from 1 to 0. I guess that means that the bulb is good ?
I put the probes on the tits of the light socket and it changed from 1 to 0. I guess that means I have a complete circuit and that's good ?
I felt smart and techy for a minute there. What now ? What's the process for finding the problem ? I know nothing about electrics.
There's 3 wires that go to the tail light socket. My headlight and horn work, fwiw.

[fastisbetter]

is it an led or filament unit? First thing would be to check your voltage in the socket or last plug in the circuit. With the bike running you should get between 13 and 15 volts DC. And fwiw, you shouldn't check resistance while the circuit is live as it will smoke your meter.

[Brian VT]

The bike wasn't running when I used the meter. The bulb is filament type.
Does the lack of resistance suggest that all my connections and wires are good or does it mean nothing ?
Do I check the voltage between the 2 tits that the bulb contacts ? (there are 3 wires going to the socket)

[motogroove]

Originally Posted by Brian VT

The bike wasn't running when I used the meter. The bulb is filament type.
Does the lack of resistance suggest that all my connections and wires are good or does it mean nothing ?
Do I check the voltage between the 2 tits that the bulb contacts ? (there are 3 wires going to the socket)

Two yellow and one black?

I am sort of a dim bulb with electrics too. But here's what I would check:

Check each wire to see which one has continuity (zero resistance) to the frame (i.e. find which one is the ground wire). Probably the black one is ground.

Then check between ground and the others for voltage.

-dean
just guessing

[fastisbetter]

you should usually be able to tell if a filament bulb is good by looking at it, the filament still in contact with both sides and not broken anywhere. But failing that, I would think there should be a very small amount of resistance. If the bulb is blown you will have infinite resistance(I or 1 on your meter) The case of the socket that contacts the metal case of the bulb should be the ground and the tits will be one for brake and one for taillight. When checking voltage you could wrap a bungee or something around your brake lever so you don't have to hold it. If you dont get voltage at the socket, you will have to start tracing wires and checking for voltage at each connection starting at the socket and working your way back to the stator. Since your headlight is working I would suspect that there will be no problem with your stator, but maybe someone will know more about your particular bike. Check your voltages and let us know

[Brian VT]

So...to check voltage I put one probe on a "tit" and the other on a ground ?

[motogroove]

Originally Posted by Brian VT

So...to check voltage I put one probe on a "tit" and the other on a ground ?

Yes. That should work.