Author Topic: Vetter to regular headlight woes  (Read 2688 times)

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Offline robdrobd

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Vetter to regular headlight woes
« on: July 12, 2012, 10:06:12 AM »
The bike I bought, 75' cb750k had a vetter fairing. When I bought it there was no headlight or fairing. I am trying to wire the new headlight(no fairing) and have come across the following problems. The wiring diagram shows a brown and red wire coming from the fuse box and connecting to the other brown and red coming from left control. My problem is this. I have two brown and red wires coming from the main harness. One is connected to the left control, the other is connected to a brown and white (turn signal). My new headlight won't work at all. Also, my tail light comes on solid when my key is in the position past "run". Any ideas?

Offline Sniper X

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Re: Vetter to regular headlight woes
« Reply #1 on: July 12, 2012, 10:11:44 AM »
the position past run is parking light so I THINK that is normal. Let me look for a wiring diagram and get back to you.
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Offline Sniper X

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Re: Vetter to regular headlight woes
« Reply #2 on: July 12, 2012, 10:14:42 AM »
Check this out..

1973 CB350 Four, 1969 CL350 Scrambler (2) 1985 BMW R80RT.

Offline robdrobd

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Vetter to regular headlight woes
« Reply #3 on: July 12, 2012, 10:19:25 AM »
Ok, brake is fine. That's just the parking position. Thanks for that. But the two Brown and Red's coming from the main harness has me stumped. Also, there is a 10amp fuse in the box for the headlight, but the wiring diagram shows a 7

Offline robdrobd

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Vetter to regular headlight woes
« Reply #4 on: July 12, 2012, 11:28:38 AM »
Any ideas why it had two Browns with red stripe? Also, would switching to 7 amp fuse from 10 make any difference?

Offline robdrobd

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Vetter to regular headlight woes
« Reply #5 on: July 12, 2012, 12:49:19 PM »
Cleaned everything, changed fuses, reconnected all wires and used one of the br/r wires. No headlight. Then I used the other one. No headlight. What gives? Is the harness supposed to have two brown, red striped wires? Can someone confirm this?

Offline TwoTired

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Re: Vetter to regular headlight woes
« Reply #6 on: July 12, 2012, 01:27:26 PM »
The Honda shop manual has a wire diagram for the K5.  I find that shop manual pretty handy.

Br/R is headlight power from fuse to LH control.  There should be a male and female connector, that simply plugs together.

There are a bunch of Br/W wires.  And they are all connected together.   The Headlight fuse gets its power from the Br/W wires via a solder connection inside the harness. 
There are also B/R wires (Oil pressure),  and Bk/W wires (coil power.

It is interesting that the diagram posted above claims K3-K7 are all the same, where the actual Honda shop manual, has four different diagrams for those models.

I wonder who's fooling who?
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Offline robdrobd

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Vetter to regular headlight woes
« Reply #7 on: July 12, 2012, 01:40:22 PM »


"Br/R is headlight power from fuse to LH control.  There should be a male and female connector, that simply plugs together."

This is my dilemma, TT. I have two Br/R male connectors coming from my main harness. One of then was connected to the female version. The other was connected to a Br/W. I have the original wiring diagram that came with the owners manual, but it only shows one Br/R coming from the main harness.

Offline Sniper X

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Re: Vetter to regular headlight woes
« Reply #8 on: July 12, 2012, 02:21:49 PM »
Wait, did you say it CAME without a headlight at all? If so I am statring to believe there is a reason for that, that somewhere someone rube goldberged the wiring and screwed something up. If you look in the light switch, follow the wires from it to where the headlight is supposed to be and if the wires don't go from there to the front of the frame, you need to re run them or at least test those points with a VOM at the switch to see if current is coming from there to power the headlight.
1973 CB350 Four, 1969 CL350 Scrambler (2) 1985 BMW R80RT.

Offline robdrobd

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Vetter to regular headlight woes
« Reply #9 on: July 12, 2012, 02:24:45 PM »
As you can see I have two Br/R wired and this little jumper thingy coming from main harness. I traced the two Br/R and they end in the safety starter connector in the side panel. Here's a pic

Offline robdrobd

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Vetter to regular headlight woes
« Reply #10 on: July 12, 2012, 02:26:58 PM »
The bike had a fairing, but PO removed it before I bought it. I think the vetter had a built in headlight so when I got it there was no headlight at all.

Offline robdrobd

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Vetter to regular headlight woes
« Reply #11 on: July 12, 2012, 03:56:41 PM »
I painted my headlight ears and bought a light with an all metal bucket so it doesn't contain the grounding nuts. Could the paint on the ears be preventing the bucket from grounding and needs to be sanded off? Would that keep the light from working?

Offline robdrobd

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Vetter to regular headlight woes
« Reply #12 on: July 12, 2012, 04:50:07 PM »
Ok, my wiring is spot on perfect now. I am 100% positive. The only thing not working is the headlight and the high beam indicator. Also, this is a new aftermarket headlight with an H4 bulb, 60/55. Will that make a difference? Is the bulb bad? How can I test the bulb?

Offline robdrobd

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Vetter to regular headlight woes
« Reply #13 on: July 12, 2012, 05:55:34 PM »
Anyone?

Offline robdrobd

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Vetter to regular headlight woes
« Reply #14 on: July 12, 2012, 06:24:11 PM »
Just tested the bulb on the battery and it worked fine. Maybe there isn't enough power left to run the H4 light?

Offline TwoTired

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Re: Vetter to regular headlight woes
« Reply #15 on: July 12, 2012, 07:25:51 PM »
Do you have a voltmeter?
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Offline robdrobd

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Vetter to regular headlight woes
« Reply #16 on: July 12, 2012, 07:33:05 PM »
I don't have a voltmeter. Is it possible that there isn't enough power left to illuminate the bulb?

Offline rboe

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Re: Vetter to regular headlight woes
« Reply #17 on: July 12, 2012, 08:22:49 PM »
The bulb is like a resistor so low voltage will just give a dimmer light. You need a volt meter (Lowes, Ace, Auto Zone sell these inexpensive little units that should serve your needs for now). With that you can make sure those brown wires have juice coming out of them (using the volt meter you can ground it right at the battery to by pass any grounding issues).

With the volt meter you can test where the voltage stops, if the switch works; useful information in tracing things out like this. A simple continuity checker, basically a 12v light bulb with two leads would also work but will not reveal your voltage which would answer your low voltage question.

When I installed a couple Vetters back in the day, and serviced some bikes with Vetters, the wiring could be very iffy. Not exactly state of the art and if it was owner installed, an owner with few skills, all bets are off on what was done to get the light to work.

With my Moto Guzzi Quota we used relays to run battery current directly to the headlight with a low current light duty wire to the switch so we could maximize the light produced by the bulb. Quota's are notorious for very poor lighting; this is something to consider in your application too. I have no feel for how much power the 750 will produce but back in the day there was little need to give a motorcycle a big generator  until Goldwings came out and folks wanted to light them up like diesel tractor trailers.

Painted light buckets could indeed cause  you poor grounding. It would not be a bad idea to run a ground wire from the frame into the bucket to provide a ground path while keeping the paint intact.
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Offline Don R

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Re: Vetter to regular headlight woes
« Reply #18 on: July 12, 2012, 09:02:09 PM »
It may have been mentioned but the headlight ears are insulated from the chassis by rubber mounts. You need to ground them to a green wire somehow. if you have no hi or low beam that indicates the power is not going to the dimmer switch. I think a 75 had the dimmer on the left side. Get a test light and locate the wire going to the switch, then locate the wire coming back from the switch. Test them both. A test light with a pointy end can be used to pierce the insulation to check if you don't want to unplug.
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