Electrical problems

Just about every motorcycle mechanic I talk to has one thing he prefers not to deal with: electrical systems. It's not necessarily because of the occasional shock or burn from being the ground receiver of an open circuit. (12 volts is nothing compared to the 240 coming out of a laundry machine outlet.) The bad part is the intermittent working and not-working of components. Or worse, an engine not working after virtually everything and the electrical has been checked.

The electrical system on a motorcycle is like a body's circulatory system. Blood pumps through the body from the heart-- like energy from a motor to the rest of the bike. The heart muscles contract because of signals from the brain-- like the ignition sending impulses to the motor which mix with fuel causing explosions in the engine. Like the body, which can lose power if loses blood, a motorcycle needs its electrical system in sound shape in order for everything else to operate well.

When Jason and I bought Molly, a 1981 Honda CX500c, the previous owner said he had to put her on a trickle charger every time he parked overnight or longer, or else she wouldn't start. A mechanic told him it was a bad rectifier. Bad doctor. The rectifier, as we checked, is in perfect working condition. Something else was wrong.

One thing that was wrong with Molly was that the circuits were not properly closed. Like a blood vessel, which is a continuous path through the body from the heart to body parts and back to the heart with a pit stop at the lungs, an electrical circuit runs from a power source (the battery) to the components and back to the power source with a pit stop at ground. Just as blood needs oxygen from the lungs to continue doing its job, electricity needs ground to fulfill its purpose. (If you look, you'll see that one of the terminals of your bike's battery is connected to ground. It could be the positive terminal or the negative depending on the model of the bike.) Molly's wires had open contacts; uninsulated copper "bleeding" power before reaching the bike's components. In electrical terms, her power was going straight to ground. This was why the previous owner could not leave the bike parked overnight without charging the battery. Her power was terminally bleeding. (hehe)

Electrical system rule #1: All complete circuits must go to ground.

Molly had incomplete circuits. Before power could reach components, energy was wasted via uninsulated copper touching other metal parts on the bike, or moisture in the air. A symptom of this was the dry battery acid sprayed all over the starter solenoid. (Fortunately, that still works.) To fix this, I used heat-shrink tubes made out of silicone, a rubbery polymer made from the natural element, silicon. The wires were cut, which were then run through pieces of tube long enough to cover the bare areas, and soldered. Then the tubes were placed over the bare copper and heated using a heat gun, causing the tubes to shrink around the copper, insulating it from moisture and power shorts.

Copper wires in circuits are covered with usually vinyl or silicone. Personally, I prefer silicone because it has a higher heat resistance than vinyl, and its base is silicon, not petroleum like vinyl. (Rid the need for oil! End the war!)

All circuits on a bike are grounded (attached to the bike frame). Take blinkers for example. Some bikes have blinkers with one wire coming out of them. That wire is to be connected to the power source. When it has only one wire, it means the part to which the blinker is attached acts as ground. Look at a motorcycle frame carefully, and you'll find that all a motorcycle's components are connected by metal. Even the battery has a line wired to the frame. The front forks are sometimes connected to the frame with metal parts which act as electrical conduits. Other times wires come from the front forks and connect to the same metal frame as the battery.

The real difficulty of repairing electrical systems on motorcycles is the sorting through the complexity of wires. It's kind of like taking all your blood vessels and figuring out which tube goes to what body part.

Try to solve the problem before spending too much money and spending a mechanic's time

A motorcycle is an isolated electrical system. When it all works correctly, the battery provides the energy to power an initial spark, which when mixed with gasoline, gets the motor running, which then causes the alternator rotor to turn, building up an electrical charge that is sent to the rest of the bike including the battery which then recharges. Turn off the ignition switch, the engine shuts down, lights go off, and the battery stops charging.

If a light doesn't work, its circuit is broken. Finding where it's broken can be a challenge, especially if you don't know all the parts within the circuit. This is where electrical diagrams come in handy. Even if you don't have the exact diagram for your particular model, it's possible to figure out the problem. Most motorcycles use different color wires for each circuit. So, if your headlamp's wire is blue, and you find a blue wire elsewhere on the bike, there a high probability that that blue wire is connected to the headlamp.

To find out where a light's circuit is broken, answer these questions:

1. Is the ignition switch on? If no, turn it on. If yes, go to 2.


2. Do other lights work? If no, charge your battery. If yes, go to 3.


3. Does the bulb have a broken filament, or is it burned out? If yes, replace it. If no, go to 4.


4. According to the wiring diagram, is the light directly connected to a fuse? If yes, go to 5, if no, go to 6.


5. Is the fuse broken? If yes, replace it. If no, go to 6.


6. Is the bulb connected to a power source and is it grounded?

If you notice, there's no step after 6. That's because even if you think the answer is "yes," it might not be. This leads to rule #2.

Electrical rule #2: Connections must be clean.

If you have an old bike, the connections probably need cleaning. All it takes is some fine sandpaper-- 220 grit is dandy-- and a little scouring. It doesn't have to be shiny. Just get as much dirt or corrosion off as you can.

In a perfect electrical world, wires would be uninterrupted, joined by a clean and solid soldering job. But since motorcycle parts are often replaced, wires must be able to disconnect in order to remove bike components. Some manufacturers use standard connectors that can be bought at electrical supply stores. But other companies make their own connectors. Whatever way wires are connected to each other and to components, the connections must be clean-- metal-to-metal. On my old Honda, if I have to replace connectors, I use standard blade connectors with silicon covers.

In the case of blinkers, as mentioned eight paragraphs in, ground might be the fixture itself. In that case, either a new fixture is needed or an extra wire connected to the bike frame. Just did that (added a wire) to Molly the other day to get her to pass inspection.

One day, maybe, I'll go into how parallel and series circuits work and how to make sure one circuit is insulated from the others. For now, I hope these two electrical rules help you in your quest to get your bike working: all circuits must be grounded, and all connections must be clean. Even though my blog is called "Learning to Ride," if you're bike is broke, you can't ride it. So, learning to fix it is learning to ride.

Fixing Molly, a 1981 Honda CX500c

Here are pictures of all the things done to Molly to get her to work well.

When we brought the bike home, the first thing we did was change the handlebars. CX500 Customs have hangar handlebars like cruisers. The hand position is really uncomfortable and can cause tendinitis. Besides, I have a fractured forefinger (hairline probably), and during the ride home, whenever possible I had to shake the pins and needles from my hand. Not good positioning.

Testing different handlebars

The right blinker wasn't working and the battery wasn't holding its charge, so Jason tested the rectifier-- that was good-- and I removed the headlamp to look at the wiring. What a mess!

These wires were hanging out the back of the headlight fixture, tangled in a ball wrapped in electrical tape.

Someone had spliced in extra wires to attach flasher relays. A bike only needs one flasher relay connected in series to the switch. But this bike had two flashers wired in after the switch. The right flasher was wired incorrectly, hence non-working. Plus, hot wires were exposed, which means the power was going directly to ground. That's why the battery was discharging. Evidence of the discharge showed up on the starter relay near the battery, which was sprayed with dried battery acid.

I untangled the ball, removing connections that were done by a hack, and started pulling wires through the headlamp fixture, where they belong. There were lots of cut wires!

Untangled!

After getting all the wires through, I called it a day. Next was retrieving the wiring diagram to rewire and get everything working properly.

It already looks better.

Since the harness is different from the original, I had to go by several wiring diagrams in order to understand which wire went where. Unfortunately, each diagram had a different key. One diagram used the letter "B" for Black. On another plan, it was Blue. Aw, geez. I had to make lots of notes.

This is the original Honda CX500 wiring diagram before the Custom came out. This diagram helped most. Some of the differences were drawn in. All the dots that are circled is where wires needed reconnecting. If you double click on the picture, you can see it bigger.

This next diagram is the addendum to to the Honda manual. Unlike the harness Molly has, the following diagram has only one black wire in the harness. Molly's harness has two black wires running through. This explains why the previous electrical hacker cut so many wires trying to make it work.

This is the addendum to the wiring diagram with notes for the different models. I circled the power line connectors to figure out why Molly's lights weren't working properly. That didn't help much. Though, it was from remembering this diagram that I realized that that circuit simply wasn't getting power.

Did I mention I made lots of notes?

Since the existing diagrams didn't match, I made my own diagram to figure out the problem.

This is Haynes' Honda CX500 wiring diagram. I used this to figure out which power line needed a splice. See where it says "4 way connector"? That's where the additional brake lights are going to go after reducing blinker power.

To get the blinkers working, I used the gray and black wires in the harness, unlike the original CX500 manual, which says they run through the headlight fixture.

Flasher relays are polarized. You have to match the correct terminal to the power source. In this case, the black wire goes to the positive side of the relay (I think. I'm not sure because this relay has an "X" instead of a "+"). The gray wire returns to the lights via the switch. In my sketch, I drew two power sources: one through a fuse, the other from "power." I'm not sure why I drew it that way. Probably because of all the diagrams I was trying to reference. I ended up going through a fuse, because of this diagram I found on a website.

It looks like the person who drew this might be an engineer. I think I'll trust this and go through a fuse.

There was a spare brown wire, probably for cops to attach a siren or something. I used this for the blinkers since this line only powered the lights in the tachometer and speedometer. If I ever put in something like handwarmers, I'll reroute the blinkers to the main power line and install a heating element through that fuse (maybe). Besides, my new blinkers will use just a little power and will need a thermistor or some other resistor to keep them from shorting. But, hey, if you know better what to do, please comment!

Turn signals only need one flasher relay. The switch controls which lights are connected to it. (That's soldering flux in my left hand. It's all Radio Shack had for flux.)

After testing the relay, I had to clean up some of the connections, and tighten others. Once all the connections were clean and insulated, I put the wires together for the headlight to go back on. The 7-volt regulator (not the same as the rectifier/regulator combo unit) sits outside the fixture. Wires were wrapped and pulled out to make space inside the fixture. In the end, all the original plastic connectors, and newly soldered connections were inside the fixture.

The wires reconnected and reorganized! It's not advised to use those blue connectors permanently, by the way. But making sure everything worked, it sure was handy having them. When I change the bulbs to LEDs, I'll solder and heat shrink the connections.

She works! (Picture to come.)

1981 Honda CX500c wiring

She works! Two nights ago, after getting home from the shop, I looked at the Honda manual's electrical diagram thinking about why the front brake, headlight, and running lights work, but not the rear brake, turn signals, oil and clutch lights.

The problem with figuring it out was that the harness did not match the model bike I worked on, and it wasn't the same as any of the 3 diagrams I used. So, I had to really think about how power is routed. Fortunately, once I matched the connectors that go in the headlamp fixture to the ones in the diagram, I could see that only 4 or 5 wires were different. (When we bought the bike, the wires were in a tangled ball outside the fixture.) Maybe there were more mismatched wires, but there were only a few that mattered.

Power for the lights must come through the ignition switch. The lights I mentioned-- front brake, headlight, and running lights-- did. The rest were powered by...? That was the problem. Those were connected directly to the voltage regulator attached to the rectifier. But power doesn't come through there unless the engine is running. The oil and clutch lights must come on before the engine is started. So where was the power going to come from? It also had to come from the ignition switch.

The original Honda plan has a black wire that appears to end on a connector. That connector was obviously different from what I had on the bike. Sure enough, that black wire on the plan was on the same circuit as all those non-working lights. The original connector probably had connection to power in it. But my connector is different; it doesn't have that connection.

I wanted to put these lights on a different circuit from the front brake so that in case one circuit went bad the other circuit would still have a brake light. This second circuit also had to come from a 10amp sub-fuse. The headlamp needs its own fuse since it uses the most power at about 40 watts on low beam. The brake light is 27 watts, each turn signal, 23W. The lights on the indicator panel use 3-4 watts each.

I had to find a battery-powered wire to splice into. Fortunately, on this harness, there was a spare brown wire routed via the ignition switch from a non-headlamp fuse. The only other thing this circuit powered was the speedometer/tachometer night lights. I connected this brown wire to a spliced-in black wire from the turn signal circuit.

Unfortunately, with everything wired, too much power was needed to make everything work through one sub-fuse. I ended up disconnecting the front running lights (turn signal lights that stay on when not indicating a turn) in order to have enough power to run the essentials-- brake light, running tail light, oil and clutch indicators, and turn signals.

I have to say, I really enjoyed working on this project. Moreso than other kinds of projects. Writing my book wasn't even as fun.

Now that I can get the bike inspected, next electrical step is to replace the turn signals for LEDs. They will draw less power. Then I'll be able to reconnect the front running lights. (I'll swap those, too.) I also want to add 2 more brake lights to make a braking triangle. This could potentially prevent being rear-ended by absent-minded cagers.

Can't wait to ride! Snow, go away!