Motorcycle Repair/tail light


Bill - I have a 1969 Honda CB 350 ( I bought it in 1970). I renovated it over the last two years and have one thing left to fix. The tail light will not go on when I depress the foot pedal, the hand brake works just great. I replaced the switch with no help and even shorted around the switch to no help. If I run a power line from the battery to the green/yellow line the light works. The headlight hi beam indicator won't work also. Suspect the regulator might be the problem but have no idea why.Can you help getting this old favorite up and running>

John, Check the wiring diagram here:

Use a 12v test light to probe into the brake switch on the black wire (switched hot) and then check the green/yellow wire side while depressing the brake pedal. You may not have it adjusted fully so that the plunger is making the connection internally for the switch.

I would also check the tail light socket to see that the ground path is all intact. Honda used a fine braided wire from the socket base to the mounting plate, which eventually makes a ground connection. If you have an open ground, the brake light will try to go back through the tail light wiring electrical path and you get a funny dimmed light at the back.

If your high beam is working at the headlight, then check the condition of the indicator bulb first, then the connection at the high beam wiring inside the headlight, as well as the ground to the rim and headlight shell.

A 12v test light will help you follow the voltage paths, but be mindful of open grounds, as well.

The charging system has nothing to do with this problem unless the battery voltage is dropping down into the 10v range.

Bill Silver

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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