Topic: Brake light but no tail light??

[howardstapley]

Does anyone know why this would be?(1974 CB350F) Thanks to everyone for help with the choke question.

[JonnyHonda]

I don't know the 350, is it single stop/tail bulb or two  bulbs

[KB02]

Do you have abad filiment in the bulb? Or a bad power wire to it?

[Lee]

This is a good wiring diagram for the 350. It may be of some help.

http://oldmanhonda.com/MC/wiring350F.html

As a matter of fact, I'm having the exact same problem with my 400/4. I'll keep you posted.

Lee

[jaknight]

Hey HowardStapley,

     I once had the same problem on my '74 CB750 K4.  I went through all the wiring, checking connections, cleaned all connections & groundings...... Even recharged the battery just to make sure it was really strong enough (yeah, I know..... dumb).  I did everything except the most obvious (electrics are my worst point about engines).............

     I finally checked the tailight bulb.  On mine, it is a "2 stage" bulb.  Part runs the tailight, the other filament runs the brake lights when applied.  Sometimes the bottom of the bulb itself has been over "crushed" and no longer makes good electrical contact, so that even with good filaments, the bulb no longer functions correctly.  The bulb cost me like 75 cents and everything has worked fine since.  Just in case you have not done so, check your bulb filament and if you need one, replace it with the same bulb number/ratings that your original has.  It might be worth buying a new bulb irregardless........ You never know......

     ~ ~ ~ jaknight ~ ~ ~

[Lee]

Hi Howard,
In checking on my 400/4 (US model). I noticed I didn't have power to the solid brown wire at the rear fender (ignition on). The wiring diagram shows the tail light system getting it's power from the dimmer (HI-LOW) switch (check my prior post for link) but my system is not set up that way. Check your solid brown wire at the rear fender. If no power, check to see if you have a connection similar to the one in the picture below. It's the only "cross-color" combination on the entire bike. Black connects to Brown (w/blue coller). See pic. If you don't have a similer connection, open up the dimmer(HI-LOW) switch, if there is a brown (w/white stripe) there. That's where the tail light system is getting it's power. If there is no brown w/white stripe in the dimmer then you're missing the connection as in the picture. In doing my restoration I didn't know what the wire was for and left it off. Duh, guess now I know.

Hope that helps. I assume you've already checked the bulb.

Lee

[Chris Schneiter]

One other option...mine's out too on my 750, but the last time it happened, I found a bunch of connectors under the seat, and one was slightly disconnected.

[DrMark]

Just to be sure.....do you have the key turned to the correct position? On my 1978 CB550, I have to have the key turned all the way to the right to get the tail light to come on for night riding. Just turning the key to the first detent will give me power to the bike, turning it to the next detent gives me power to the lights also. Maybe this will help.

[howardstapley]

SO MANY BUTT CONNECTORS!!! I’ve had a few cars that had some "home body" electrical but this is unreal. Found the loose one but im going to wait and solder it back. Damn... Thanks allot guys for the ideas, I wouldn’t have runt he lines otherwise.