Topic: Another Headlight issue

[Ashleyd205]

Hey guys.  I'm still fairly new to all this stuff so sorry if I'm slow or stupid.

So, I've been racking my brain over this for a few weeks now trying to figure out my issue.  I have a 75 CB550. About two months ago I was riding to work and noticed my headlight was on, as I was parking I noticed it had turned off and would not turn back on. I thought the bulb had blown so I replaced it, which did not fix the problem. 

 I have taken the bulb out and used a mutli-meter and it get between 11-11.8v at idle and of course goes up with the rpms. Replaced the voltage reg, fuse block(which had melted), and rectifier. I recheck all the wires in the headlight bucket earlier today and I'm just stuck.  Hope someone can help guide a lost sole!

[MoMo]

do you have 12v at the headlight socket on the white wire with the switch on low beam and 12v at the blue when high beam is activated?...Larry

[GEARBOX]

I believe you should have three wires to the head light like on the 750's.  Blue is high beam, white is low beam and green is ground.  Are you taking the reading using the green as the ground?  Or using another common ground (i.e. frame)?  If you are getting power using a frame ground, test the green headlamp wire ground.  Sounds like the green wire may have pulled out of it's connector or something else is affecting the grounding of the green wire.  Good luck, Allan

[calj737]

Replaced the... fuse block(which had melted)...

And here is the problem. You can either fix the symptom or solve the problem. If your fuse block melted, you suffered some serious electrical issues. Your wiring in the headlight bucket might look okay, but it probably isn't. Also, the switch controls on the LH and the RH need to be inspected! Fuse blocks don't "melt" because they're old. They melt because they're really frick'in hot. And they should not be that hot. The fuse should blow before allowing that, and it obviously didn't.

Some a few questions:
When you couldn't get the light back on, did you attempt to jump the bike with a car?
What led you to replace the VReg and Rectifier? Was this part of your troubleshooting regimen or maintenance?
What wattage bulb are you running in the headlight?

Any other electrical history on huge bike to help identify this issue?

[bjbuchanan]

Test voltage at the back of the headlight, once it gets around 11v it isn't gonna do anything.

My best guess is that you have a bunch of dirty connections due to time. Clean all of your bullet connectors with scotchbrite, not sandpaper because sandpaper removes material. Use QD electronic cleaner after cleaning. A .17 bore rifle brush gets the female bullets pretty good.

Heat comes from resistance, resistance is usually due to corrosion. If the fusebox melted that is a huge clue.

If you get really adventurous you can try depinning your plastic connectors using a cotter pin. They get funky too. At the least shoot them with the contact cleaner. Throwing parts at the bike isn't gonna do the job

[Ashleyd205]

do you have 12v at the headlight socket on the white wire with the switch on low beam and 12v at the blue when high beam is activated?...Larry

yes both have about the same voltage when i switch over from low to high and reverse.

Replaced the... fuse block(which had melted)...

Some a few questions:
When you couldn't get the light back on, did you attempt to jump the bike with a car?
What led you to replace the VReg and Rectifier? Was this part of your troubleshooting regimen or maintenance?
What wattage bulb are you running in the headlight?

1. No, i didnt use a car to jump the bike.
2. a lil bit of both. i knew the PO had done a hack job on the wiring with the headlight when i got it and the fuse block was already botched figured it wouldnt hurt anything.
3. 60/55 watt

Test voltage at the back of the headlight, once it gets around 11v it isn't gonna do anything.

My best guess is that you have a bunch of dirty connections due to time. Clean all of your bullet connectors with scotchbrite, not sandpaper because sandpaper removes material. Use QD electronic cleaner after cleaning. A .17 bore rifle brush gets the female bullets pretty good.

Heat comes from resistance, resistance is usually due to corrosion. If the fusebox melted that is a huge clue.

If you get really adventurous you can try depinning your plastic connectors using a cotter pin. They get funky too. At the least shoot them with the contact cleaner. Throwing parts at the bike isn't gonna do the job

I actually did i thorough cleaning of all the electrical connections front and back when i replaced the fuse block and reg. 

[MoMo]

H/l still inop with 12v at the proper wires?  Try  running a jumper from the green ground at the h/l socket to a good clean ground...Larry

[Ashleyd205]

Larry,
I tried that today and still nothing. Even used a multi meter and got the same volts.

I have been thinking and searching for a cause and wanted to pass this by everyone. Could it be the starter switch? I had issues with it not wanting to start months ago. Took it apart and cleaned everything and put it back.


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[bjbuchanan]

Yeah, k6 has a combined starter and headlight switch. Still doesn't explain why you get 12v at the headlight all the time , that isn't a bad switch. Bad switch wouldn't pass 12v through

[MoMo]

If you have 12v at the headlight socket, the light must work-only problem would be a bad bulb or lack of ground...Larry

[Ashleyd205]

If you have 12v at the headlight socket, the light must work-only problem would be a bad bulb or lack of ground...Larry

Tomorrow I should have some spare time and will check to make sure the bulbs are working, and will chase down the grounds and see what I can come up with.


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[Bodi]

A high resistance connection will show 12V (or whatever) at the headlight with the light disconnected, but drop to zero with a load. So getting a volts reading with the headlight disconnected isn't conclusive.

[Ashleyd205]

A high resistance connection will show 12V (or whatever) at the headlight with the light disconnected, but drop to zero with a load. So getting a volts reading with the headlight disconnected isn't conclusive.

Bodi,

You were right.  I made sure that the headlight actually worked but hooking it up straight to the battery.  Then when I connected it back correctly, 0 volts.

I am new to electrical so I am totally lost on what the issue is.....