Topic: 1982 cb650 Tail light dosn't work

[ofer]

Pleas help:
The problem is that the tail light dos not work when Ignition switch is on.

When Ignition switch is on the head light works and signal lights are working. Tail light dos not work
when Ignition switch on park the tail light works and the head light dos not work .(like it should)

My suspicions is that the ignition switch is failing.

I took apart the tail light, the head light and the ignition switch.

I checked the wire on the bike withe 12V tester and continuity tester. here are the results :
 
1. no power (no 12v) coming to the  brown wire in the tail light when ignition on. (not OK)
2. when ignition switch on park there is power (12V) on the brown wire.(OK)
3. The brown wire on the tail light is connected to both brown wires on the ignition Harness Loom port and connected to the brown wire port on the head light (witch is not connected to any were just empty port)(OK)
4. Ignition switch works Ok -
       when in off position there is no continuity between any ports on the ignition switch.
       when in on position there is continuity between black and red ports and between brown 1 and brown 2
       ports.
       when in Park position there is continuity between brown/white  and red ports.

So it looks like all is good just like the wiring diagram but there is no power coming to the tail light when ignition switch is on.

I dont understand from the wiring diagram from were the tail light should get the power when ignition switch is on?
There is no connection between the brown wire to a power source any were even when the ignition is on.
Thanks
Ofer

[evinrude7]

ground wires? 

[ofer]

Ground wires (the green wires in the tail light) are ok.
Good continuity to the black wire on the ignition port and to the frame.

[evinrude7]

the next thing i would do is disassemble the ignition switch and clean up all the contacts, check for loose solder to wire connections, grease it up and put it back on the bike.  then again i probably have less wiring experience than you but that's my 2 cents.

[HondaMan]

Try this: find the fuse that is marked "Tail" or "Taillight" and clean it, and the contacts, and make sure they are ALL clean while doing this stuff. Then take a meter and check from the chrome of the taillight housing to the Green wire under the left side cover (any Green there will do) to make sure it has less than 1.5 ohms resistance.

[evinrude7]

this is what i was shooting for in the first reply, check the ground.  +1 ^^^^^

[ofer]

Cleaned the fuse connections and the tail light works.
So simple.
Thanks guys.