1979 CB650 tail light

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

saber
Posts: 40
Joined: Thu Jan 31, 2013 6:46 pm

1979 CB650 tail light

Postby saber » Wed Aug 31, 2016 11:13 am

Hi Everyone,

You helped me get my bike on the road two years ago. The 1979 CB650 has been dependable until this weekend.

The tail light does not light up during normal driving. It lights up with the brake, but does not stay on while driving. When I put the ignition key into park, the light goes on and stays on. Any idea where to start to get this fixed? Will I need a new ignition switch? It appears that there are two brown power wires from the ignition switch to the tail light that go through the harness. But at some point, they connect to form one brown wire going into the tail light. Where is the connection? I cannot find it. Any thoughts would be appreciated?

Thanks,
Keith

User avatar
Folsoml
Posts: 1634
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: 1979 CB650 tail light

Postby Folsoml » Wed Aug 31, 2016 11:37 am

If you check in the General Discussion forum here, there is an owners workshop manual. There is a wiring diagram in the back. I would get a multimeter and check voltage starting at the light sockets. I'd then trace the harness backwards until I identified the problem.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

saber
Posts: 40
Joined: Thu Jan 31, 2013 6:46 pm

Re: 1979 CB650 tail light

Postby saber » Wed Aug 31, 2016 12:09 pm

Thanks Folsomi, I will get the manual

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: 1979 CB650 tail light

Postby Volker_P » Thu Sep 01, 2016 1:01 am

The brown cables are the power supply for the tail light. And e.g. for German bikes there is also a small 3Watts bulb in the headlight for the front parking light. This might explain no second cable comes out from your harness (US model assumed).

Here are some hints how to get into the ignition switch: viewtopic.php?f=4&t=6765&p=44997
German models have a separate steering lock so things might look a bit different for you. But you only need to get off the rear part which should be much the same again.
If you try this, be prepared for balls and springs falling out! :roll:
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

saber
Posts: 40
Joined: Thu Jan 31, 2013 6:46 pm

Re: 1979 CB650 tail light

Postby saber » Thu Sep 01, 2016 4:56 pm

Thanks for the input. Here is a question I have: If the brown wire associated with the tail light when the bike is running has power coming out of the ignition switch but a break at some later point, could I just splice that wire with the other brown wire? The other brown wire lights the tail light while the ignition key is in park so I know it does not have a break? Hope to work on this problem this weekend.

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: 1979 CB650 tail light

Postby Volker_P » Fri Sep 02, 2016 12:44 am

saber wrote: Here is a question I have: If the brown wire associated with the tail light when the bike is running has power coming out of the ignition switch but a break at some later point, could I just splice that wire with the other brown wire?

From my understanding of the the US model tail light circuit the brown cables are already "spliced". The ignition switch supplies 12V on the parking and on the "on" position alternatively to both brown cable ends. For you probably at "on" neither of the two get 12V or the "on" branch of the brown cable is damaged or disconnected or has poor contact at the ignition switch.
Find out with a multimeter before you start further experiments.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

saber
Posts: 40
Joined: Thu Jan 31, 2013 6:46 pm

Re: 1979 CB650 tail light

Postby saber » Fri Sep 02, 2016 1:55 pm

Thanks Volker. ..... good points on what to look for.


Return to “Technical Discussion”

Who is online

Users browsing this forum: No registered users and 37 guests