Topic: Oil & neutral lights work - nothing else! '71 CB500

[Tugboat]

Just got finished wiring up the CB500 I've been rebuilding. I turn the key and all that works is the oil & neutral lights... no headlight, no blinkers, no brake light... nothing. I've never worked on electrics before and don't have a multi-meter at hand. Any suggestions about where to start?

[buffaloejon]

Get a multimeter. Otherwise you'll be chasing invisible problems.

But without that, check all grounds, and then check all connections. I would say grounds first, as well as where they hook into the ignition circuit?

Just going out on a limb, trying to be helpful!

BTW, did you totally rewire from scratch, or re-use stuff?

[rklystron]

+1 on the Multimeter. They are very cheap and easy to work with. It's a necessary tool for the tool box and will make your life happy again.

[Tugboat]

It's the stock harness. The bike only has like 12k on it and was kept inside.

[Goldbug]

I say ignition. An EMGO ignition should run no more than $20 on ebay and take no more than a few minutes to install. My '73 CB500 did the same thing, plus other weird stuff.

But a multimeter will tell for sure. They are like <$20 at auto parts stores.

If not then make some simple jumpers out of alligator clamps so you can bipass stuff to figure out where the problem is.

Electrical problems are usually pretty easy to solve unless they are intermittent, then it's more of a pain.

[rklystron]

Unless you have some way to determine where there is and where there is not voltage (12v) you will have little change of solving you problem of unless course it is obvious. A connector that has become disconnected ect. Have you looked at all your connections? The black wire on a CB750 supplies 12V through out the entire system not sure if that is the same for your bike. Do you have a wiring schematic? If so look at the connections to be sure you have everything connected properly. Without a meter or a test light I dont think anyone can help you.

[Goldbug]

If you have a basic understanding of the wiring diagram for the CB500 (which I do) you can make educated guesses. I'm going with ignition switch for a couple reasons. We KNOW power is getting to the switch because the neutral/oil light work (so black wire is fine). The only thing the headlight and tail light have in common is everything up to the ignition switch, after that they diverge within the switch. The headlight could have a problem in the hand switch but the tail light would still work in that case. So you gotta think the problem is not before the switch. For everything not work after the switch you'd have to have multiple points of failure. But if you think you only have one problem then that problem is the switch.

[Tugboat]

Thanks JW - that's all I was looking for.. a place to start. Will get a meter when I get back from Barber and have a go.

[Spiider]

12v test light is a valuable additional diagnostic tool as well....and you can get one at the same place you get the multimeter for very little money.

[Tugboat]

So do you mean the actual switch that the key goes into?

[Goldbug]

Yes.

[Tugboat]

Ignition switch replaced - still nothing but oil & neutral. So what's next? Check ALL of the connections? Or does the fact that it's not the switch point to something more specific?

[TicoCafe]

I would now check and CLEAN ALL electrical connections. A small Wire brush and electronic cleaning spray solvent should speed the cleaning process.     

[Lorbaez]

did you solve the problem?

Considering that positive is common, and just this two lamps uses "independent" ground, it seems that green wires are not properly connected to the frame.
With a multimeter you have to check continuity of green wires and ground (frame).

[72500john]

try this link it may help.

http://oldmanhonda.com/MC/wiring.html

[Silverback1]

A simple solution is a test light it requires a connection to earth then check each wire with the probe (ignition must be on), the light will light up if power present.

It is quick way of finding if power present, but a Multi Meter is the best method to detect power and volts.

[Tugboat]

SUCCESS!! Was standing there staring at it, about to take the dive and start checking all of the connections when I noticed that two wires on the rear fender were unplugged (black and green/brown I think). There had been a rag sitting there and that's why I hadn't seen it before. Plugged 'em in and BAM! Checked the old switch and it was fine - which is cool since the EMGO I got as a replacement evidently sucks. SO GLAD that it was just this and not anything more serious. Thanks all!!