Author Topic: wiring headlamp - no tail light -but works w/ key on "park"  (Read 917 times)

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Offline billingstitan

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Hey all -

Making progress on my 77 CB550 rehab - will be updating my thread soon with some pics. Pulled the forks, cleaned and replaced seals and put on the headlamp tonight.

The wiring is a mess because of the fairing - but got everything mostly working except the tail light. Thought it might be a bulb - but it works if I turn the key to "Park." It looks to me as if it should have something to do with a brown wire - but I'm not seeing one in the headlight bucket.

Can anyone provide any insight or guidance, I'm curious if:

a) Is the tail light affected by wires in the headlamp bucket, or are these unrelated?

b) If it IS affected by wires in the headlamp bucket, any thoughts on what I might be missing?



Any advice, thoughts or guesses are much appreciated - most of these connections I managed to trace down between just following the wiring and using the wiring diagram ... but this one has me stumped. I'm really confused why it would work with the key in one position but not the other  :o
Calling upon my years of experience, I froze at the controls.  ~Stirling Moss

2014 Ducati Monster 796
1977 CB550K http://forums.sohc4.net/index.php?topic=138289.0
1977 CB550K
1972 CL175
2000 Kaw Nomad 1500
1992 KDX 200
2001 Honda 80R
Past Bikes:
1973 Kaw 900Z1
1970 Yamaha 350RD
2003 Yamaha VStar 1100
2001 Suzuki GS850

Offline billingstitan

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Re: wiring headlamp - no tail light -but works w/ key on "park"
« Reply #1 on: June 18, 2014, 09:58:10 PM »
Hmm ... doing some more reading on here, and it sounds like the tail is on the same circuit as the instrument lights - those are not working either.

Will continue searching, but wanted to add that bit of info it helps anyone w/ any troubleshooting tips.
Calling upon my years of experience, I froze at the controls.  ~Stirling Moss

2014 Ducati Monster 796
1977 CB550K http://forums.sohc4.net/index.php?topic=138289.0
1977 CB550K
1972 CL175
2000 Kaw Nomad 1500
1992 KDX 200
2001 Honda 80R
Past Bikes:
1973 Kaw 900Z1
1970 Yamaha 350RD
2003 Yamaha VStar 1100
2001 Suzuki GS850

Offline goldarrow

  • one day, i'll be an
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Pull all the wires in your bucket out and start cleaning each contact, plug back in color by color and follow your wiring diagram.  Should be good to go.  Don't blow up the engine now   
Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline billingstitan

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Re: wiring headlamp - no tail light -but works w/ key on "park"
« Reply #3 on: June 18, 2014, 10:45:47 PM »
I'm sure I have no idea what you're talking about  ::)

And yeah, laying here in bed almost asleep and it hits me:

It was just a f'n fuse  :P Never even checked.

I believe somewhere, twotired is rolling his eyes right now.
Calling upon my years of experience, I froze at the controls.  ~Stirling Moss

2014 Ducati Monster 796
1977 CB550K http://forums.sohc4.net/index.php?topic=138289.0
1977 CB550K
1972 CL175
2000 Kaw Nomad 1500
1992 KDX 200
2001 Honda 80R
Past Bikes:
1973 Kaw 900Z1
1970 Yamaha 350RD
2003 Yamaha VStar 1100
2001 Suzuki GS850

Offline Bodi

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Re: wiring headlamp - no tail light -but works w/ key on "park"
« Reply #4 on: June 18, 2014, 11:54:32 PM »
That was going to be my suggestion, check the TAIL fuse. The tail light wiring is stupidly complex because of the ignition keyswitch "park" function. In "Park" the tail light is powered directly from the MAIN fuse, with key "ON" it gets powered from the TAIL fuse (through the MAIN fuse as well of course).
I have yet to find anyone who has actually used the "Park" function - except to see what it does.
The other thing with rewiring is that some models without a headlight on/off switch (because of always-on laws) have an oddball jumper to suit the main harness that's made to have that switch. This ~8" long jumper is inserted into the right switchpod wiring sleeve but it easily pulls out (and is inexplicable when found on the floor if you're not aware of its purpose), plus current generic replacement switchpods don't have it. It's oddball because it has a black wire with a male bullet end and a brown/blue wire with a female bullet end: these two wires are spliced together where they meet inside the sleeving. Without it, you have no tail light except in "Park" since that brown/blue wire feeds the TAIL fuse.

Offline billingstitan

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Re: wiring headlamp - no tail light -but works w/ key on "park"
« Reply #5 on: June 19, 2014, 11:02:09 AM »
Thanks - that is good information to know.

Oddly - after replacing the fuse, one of the turn signals became like a running light (it still flashed when activated tho). So I pulled the blue/white wire, and it works fine. Buttoned it back up, and turned the key, and then the other side did the same thing.

Pulled the orange/white wire, and now they work as intended, but only one wire is connected.

Just left them that way for the moment - can't think of any hard that would come from running them like that, although I could be missing something.

Appreciate everyone's input.
Calling upon my years of experience, I froze at the controls.  ~Stirling Moss

2014 Ducati Monster 796
1977 CB550K http://forums.sohc4.net/index.php?topic=138289.0
1977 CB550K
1972 CL175
2000 Kaw Nomad 1500
1992 KDX 200
2001 Honda 80R
Past Bikes:
1973 Kaw 900Z1
1970 Yamaha 350RD
2003 Yamaha VStar 1100
2001 Suzuki GS850

Offline goldarrow

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I told you so.....

Let's try again.  Here goes

Pull all the wires in your bucket out and start cleaning each contact, plug back in color by color and follow your wiring diagram.  Should be good to go.  Don't blow up the engine now
Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline billingstitan

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Re: wiring headlamp - no tail light -but works w/ key on "park"
« Reply #7 on: June 20, 2014, 12:40:46 PM »
@ goldarrow - gotcha. Cleaned the contacts, etc. before I put the headlight can together. The issue with this bike is that the wiring was spliced, diced and black-taped to work with a Kawasaki fairing. The elec diagram is helpful, but there's still a lot of guesswork involved.

In any case - everything's up and working, so I'll leave it as is for the time being and move on to the rest of the rehab.
Calling upon my years of experience, I froze at the controls.  ~Stirling Moss

2014 Ducati Monster 796
1977 CB550K http://forums.sohc4.net/index.php?topic=138289.0
1977 CB550K
1972 CL175
2000 Kaw Nomad 1500
1992 KDX 200
2001 Honda 80R
Past Bikes:
1973 Kaw 900Z1
1970 Yamaha 350RD
2003 Yamaha VStar 1100
2001 Suzuki GS850