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Discussion Starter #1
How would I go about getting the taillight to switch on a Honda cb350 when the headlight is on? I'de assume the rear running light would be automatic when the headlight comes on but not sure if thats not the case and i would need to rewire something or if there could be a loose connection somewhere.


'71 Honda cb350
 

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You should start with the obvious - checking the bulb, since it's a dual filament, one for brake and one for taillight - and if that's good, checking the wiring connections in the headlight case. From there it could be the headlight switch on the handlebars if yours has an "off" position (prior to the headlight on at all times law). It could also be the ignition switch contacts internally not powering up the lighting circuit IIRC (brown wire on one of the switch contacts)
 

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When you check the bulb turn on the lights and check the socket with an ohm meter to see if you have power to the socket. It could as simple as the bulb not making contact in the socket. This happened to me and it can be hard to find. If no power to the socket then go with the other members suggestions.

Bill
 

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Do you have the FSM ? Factory Service Manual?

There is a full wiring diagrm in it.
Agreed it can be hard to trace in Black & White.

Attached i a COLOR Hi-Res Graphic.
Right Click - OPEN in NEW WINDOW or TAB.
And/OR SAVE-AS then put it on a USB and have an office supply shop print on a large format poster printer.
 

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Another place to look for a problem is the key switch. The brown/white & brown wires are connected together when the ignition switch is in the run position. Power comes back from the headlight switch in the brown/white wire and is connected, inside the key switch, to the brown wire that goes to the tail light.
 

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Another place to look for a problem is the key switch. The brown/white & brown wires are connected together when the ignition switch is in the run position. Power comes back from the headlight switch in the brown/white wire and is connected, inside the key switch, to the brown wire that goes to the tail light.
Yeah, that was my thought too (post #3). The contacts get corroded over years of sitting inactive and they're not hard to take apart and clean
 

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Discussion Starter #8
Will try all of the suggestions in order of simplicity and keep everyone posted. Thanks for the advice!!
 

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Discussion Starter #9
Behind the headlight the Brown (male) wire was connected to brown/white female connector and brown/white 4-way connector had an open place. Plugged the br/wt in the open spot, tail light went on!
Thanks for all the help y'all!
 
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