Basic electrical failures

No Source; Open; High Resistance; Short; Ground

Source

The Main source of power on a Motorcycle is the Battery.  The most common electrical failure is the absence of power, or a discharged battery.  The battery does not need to be fully discharged for circuits to stop functioning, as most circuits require a minimum voltage to operate.

Except for off-road bikes, most motorcycles use a 12 Volt Battery, and a minimum of 10.5 Volts is necessary for any system or circuit to function.

One system however will require a fully charged battery to operate: The Starting System.

(Pure off-road bikes often are powered by coils coupled with magnetic rotors, and are started with a kick start.)

Open

A circuit cannot function if any part of the circuit does not allow electricity to complete it’s full Path.

Starts at the source, powers the Load (or component), and returns to the Source.

Examples of Opens:

• Disconnected wire
• Dislodged connector
• Burned Fuse
• Broken switch
• Burned Load device
• Cut wire (often occurs at joints)

High Resistance

Corrosion and Sulfating

Over time, any motorcycle will accumulate corrosion in it’s connectors.  The battery posts and connections are most susceptible to corrosion.  A bluish sulfate powder will form if no maintenance is done on the battery.  It is easily removed, by simply pouring water over them, while the battery is disconnected.  The posts should be free of such sulfate.  For the connectors, dipping them in a cup of water is most efficient.  Of course, once the sulfate is removed, drying the surfaces using an air blower is a must.  Reassembling with water will cause the connections to sulfate all over again.  It is recommended to apply a dielectric grease after assembly to prevent water from entering again.  Most connectors on modern motorcycles are waterproof, and the seals should be inspected, and replaced if necessary.

In switches corrosion or burned contacts will cause high resistance.

Loose crimping of wires to connectors can also occur over time. In addition vibrations can cause a wire to fray and loose it’s conductivity.

Poor connections can cause high resistance. Loose connectors may need replacement. Pin type connectors are very prone to becoming loose, mostly by poor manipulationfrom the owner or the technician. Carelessly probing the front of such connector can cause a new failure.

Any electrical system using a brush type connection will eventually fail over time. Brushes, often made of carbon will wear out and cause a high resistance (starters, alternators).

Shorts

If any part of the positive side of a circuit (before the load device) comes in contact with the negative, a short will occur. The fuse will blow (melt), and the circuit will stop functioning.

Merely reinstalling a new fuse without troubleshooting, will cause the new fuse to melt.

Installing a higher Amp/hour rating Fuse is the worse remedy one could even think of.  This time the wires or the whole harness could melt.

Ground

This type of failure is often called as a loss of control. It can only occur in a circuit where the switch device is on the negative side of the circuit.  Yamaha likes negative switching, most other manufacturers prefer the switch on the positive side.

Some Charging systems are switched on the negative side, as do circuits with a push type switch (starter, ignition cut off…) Some safety devices are often switched on the negative side.

Troubleshooting Shorts

Once the fuse is blown, replace it by a high power bulb (brake light bulb will do).  A bulb in it’s appropriate socket with two male spade connectors can be used, and plugged in the fuses place.  If for a normal size fuse, use large male spade connectors. For Mini fuses, small male spades.

• Make the connection while the negative of the battery is disconnected.
• After identifying the circuits that were inoperable, make a diagram to identify the load devices protected by the fuse.
• Reconnect the battery.
• If the bulb comes ON brightly, either the short is prior to the Main Switch or the circuit is always powered originally (rare: clocks, memory systems…)
• If the bulb is off, turn the main switch ON, if it still isn’t lighting, you may be working on an intermittent circuit: Horn, turn signals, high beam, brake light, etc…)
• Power the appropriate circuit: If the bulb is bright, start disconnecting load devices of the circuit until the bulb becomes DIM. The last load device’s positive side that was disconnected is where the short is.
• Inspect and repair that circuit, including the load device.

Honda CB750 Tail light circuit

One of the simplest circuit to demonstrate how to create a Block Diagram, that came to mind, was the Tail Light circuit off a CB750 wiring diagram (as shown on Lesson 6).  Typically, any technician in need of troubleshooting the circuit would have to either visualize the circuit in his head, or make it on paper.  For a beginner, the piece of paper would be the best option, in order to make sure they are not forgetting anything.

Honda CB750 Service Manual original

As you can see on this Wiring Diagram, the Battery is a 12V 14AH, or 14 Amps per Hour. If the Bike was left with the key ON, and enough components were ON to draw 14A, after an hour, the battery will be flat dead.

When the key is turned OFF, the circuit is said to be open (no path), and the electricity is stopped at the Red wireentering the Ignition Switch.  That means that everything prior, is live or powered.  Starting from the battery positive post, through the heavy gauge wire connects to a Relay that contains the Main Fuse of 30 Amps.  It then flows through the fuse; comes out on a Red wire that travels all the way to the Ignition Switch.  Note that before the switch, there is a 2 Prong connector Black in color.  For more recent models, the ignition switch has at least 4-5 wires, and is a multi function switch.

When the key is turned ON and the circuit is powered (or said to be Closed), the electricity will travel (almost instantly) through the light bulbs (the CB has 2 of them), and will return to the battery through the Frame of the motorcycle.  And will keep doing this circuit until the key is turned OFF or something disconnects or opens.  I mentioned the frame of the motorcycle as it is being used on just about all motorcycles as a conductor of electricity (Automotive in general or Aviation).  The engine is also used as a conductor for other circuits.  See the two drawings below.

On all Honda’s you can assume that the Green wires are the negative side.  Every single Load device will use either a Green wire, the frame, or the engine for the return to the negative side of the battery. A few Manufacturer’s Ground wire colors:

• Honda => Green
• Harley => Black
• Kawasaki => Black with a Yellow stripe.
• Suzuki => Black with a White stripe.
• Yamaha => Black

To identify what is shown on a diagram, you will need to get familiar with the Symbols used in the industry.

Sample Symbols

Fuses are here to protect the circuits from excessive electrical flow.  They are rated in Amps according to the amount of electricity allowed to flow in each circuit.  Reminder: some fuses are used for multiple circuits (ie: Main Fuse).  Fuses are meant to prevent circuits from melting or catching fire.  When too much electricity flows through them, they are the first to melt or POP, and create an OPEN in the the circuit, rendering inoperable.  You then need to figure out why it happened, and then replace the fuse.  Failing to know the cause and fixing the cause will result in another burned fuse.

Another type of circuit protection is the Circuit Breaker, found on some Suzuki’s and Harley Davidson’s.  Those, you can, and should only reset.

Isolate an Electrical Circuit

Click to View Full Size

How to isolate a circuit from a wiring diagram?  The industry term is called, creating a Block Diagram.  From a wiring diagram, it is necessary to isolate, define, or identify what a specific circuit contains.  Let’s say your tail light doesn’t come on.  To troubleshoot the circuit, one can only suspect failure within the circuit unless multiple circuits are not functioning.  Or in the case of the CB750, if only one bulb is not working, then the likely cause is the bulb, the socket, or the wires beyond the connector of the light assembly.

One thing we know, is that it takes a few components to make this circuit functional.  Let’s make a list:

1. Tail light Assembly (2 bulb set up on the CB750)
2. The power source or battery
3. The tail light comes on when the key is ON => The Ignition Switch
4. Then lets take a look at fuses. The Main Fuse protects almost all the circuits on the bike
5. More specific, on the diagram we see a 15 Amp fuse labelled [Tail-meter others].

Once the list is done, all we have to do is connect the wires between the componentslisted.  Yes, that simple.  Now, keep in mind, that not every connection will involve a wire.  We know that in the automotive industry, they use the Frame or Chassis, and the Engine as a conductor for the Negative side of almost all circuits.

So, it you were to cut out everything out that doesn’t involve that circuit, well, there it is.

Click to View Full Size

Some technical manuals do provide Block Diagrams of circuits, but most of them don’t.

With a little practice, this process becomes a second nature, and troubleshooting an organized endeavor.  A technician who can diagnose is a technician appreciated by the customers.

Those who just try parts until they find the problem, do not stay in the motorcycle field, as motorcycle parts are double or triple or more in price.  It is a common practice of the too many auto mechanics to just replace and try.

Watts Law

What is Watt’s Law? _ “PIE ! That’s what comes to mind. Ok, that’s a joke. Actually, this is how I remember. This electrical law”

P = I x E => (PIE)

It defines the relationship between Power, Intensity of flow, and Electromotive Force.  Now we’ve seen before, that Intensity was measured in Amps and E in Volts.  Ultimately, the purpose of electrical flow is to do work.  In our uses, we need to provide the incandescence we see in a light bulb (by the way, they put glass around it so it doesn’t burn anything); a magnetic field that will rotate motor….  These are the most common applications on a vehicle.  Other less common application to create heat for various systems.

Here is how it works: The more Pressure there is, without too much opposition to Flow, the more Power we get.  In electrical terms: more Volts or more Amps => more Power.  One thing we should think is that in order to get more Flow or Amps, we need less Resistance.  As you can see, Ohm’s Law completely defined.

Automotive light bulbs are rated in Watts. One of the most common bulb was the dual filament Brake/Tail light bulb. This bulb is rated (on motorcycles) 12V 21/5W. Meaning, one filament is for 21W and the other for 5W.

Let see if you understood:

What filament has more flow? => the 21W or Brake light.

What filament has the most resistance? => the 5W of Tail light.

Needless to say, that if you manage to install that bulb 180º reversed, you’ve got a few problems.  One, it will blow your tail light fuse.  Two, the brake light will be too dim.  One of the most common mishandling of such is that it gets installed not quite 180º, but somehow across the two socket prongs in a way that it creates a short.  And then starts the head scratching about a fuse that shouldn’t blow?

Let’s get back to our application. Just a little Math.

How many Amps will flow in the tail light circuit?

P = I x E  =>  P / E = (I x E) / E  or  P / E = I

The result will be: 5W / 12V = 0.41A

So, more than likely the tail light fuse will be a 1Amp or more depending on what other circuits share that fuse.  Typically there will be a few more circuits sharing it, and what you’ll have is a 5A.  This is the type of application that concern us technicians.  Let say you want to add a new circuit with a 5W bulb, then you would know what fuse you would install in that circuit to protect it (installed in series of course).  One of the most common installations done on a bike are additional head lights.

Warning: Head lights will require the use of a relay to by-pass an original harness.  Any attempt to run 1 or 2 head lights through the OEM harness could result in melt down of the bike’s harness and switches.  We will address the use and application of relays at a later time.

And in the same way, we can calculate that the Brake of Stop lamp circuit would flow 1.75 Amps.  That is if we only have one lamp.  On many high end motorcycles, they install 2 Tail/Stop lamps, to get a safety extra bulb, just in case one burns.  Now, those bulbs are connected in Parallel.  Ok, we did not discuss the difference between a connection in Series, and one in Parallel.  Well, that will be the next topic.

On the troubleshooting side, one test can be performed to verify if a dual filament bulb is defective.  Using an Ohmmeter, you can check the resistance of the bulb.  It will require to test both filaments.  Notice how the two filaments have a common ground or negative side.  This ground is soldered to the metal part of the bulb’s body.  This body in turn is installed by a push twist action into the socket of the light’s housing.  To test each filament, you must probe from the body of ground tho one of the contacts.  Then from the same ground to the other contact.  You will get two different resistances. For the example of a 12V 21/5W or an 1157 (type of bulb), we could calculate once and for all for all 1157’s, what it should be.

For the Stop: R = E / I  or  12V / 1.75A = 6.8 Ω.  That’s in theory.  In reality it will be more like 1 Ω or less.

For the Tail: 12V / 0.41A = 29.2 Ω => in reality about 2-3Ω

One thing for sure, the tail will have more resistance than the stop.  And for a resistance test to give you an Open…  It all depends on how your meter indicates infinity. That’s for you to read your owners manual once and for all.

Ohms Law

Ohms Law basically defines the relationship between three physical properties of electricity: Volts; Ohms; Amps.

1. Volts: Also referred to as pressure of electricity. Defines movement of electricity. No Volts = No pressure = No movement. You basically have no movement when there is no path of an OPEN in the circuit. Volts are represented by the letter V. The technical term for it is Electromotive Force or the letter E. Scientists use E. Technicians use V.
2. Ohms: Represented by the Omega Ω. Define the resistance on a circuit. A circuit always has resistance. If it didn’t, your battery would explode if the wires are thick enough. Wires have a resistance. So, more than likely, they will burn up before the battery explodes. And by burning up, or melting down, they will create heat and an open in the in the circuit, and the process of the circuit would come to an end.
3. Amps: Represented by the letter A, define the quantity, or volume of current flowof electricity. If you were to compare a river to a hose, you could say that the river flows more than the hose. Therefore, if you bring it to electrical term: more Amps. From the idea of Intensity of flow, scientists prefer to reference amps by the letter I.

Ohms Law formulas:  E = R x I  or  I = E/R  or  R=E/I (scientific annotations)

It means that when you have two values, you can calculate the other.

Let’s say you have a battery of 12 Volts, a bulb with a resistance of 2 Ohms.  You can calculate how many Amps flow in that circuit:  I=E/R  or  I=12V/2Ω  =>  6 Amps.

Therefore if you were to install a fuse to protect that circuit, it would have to be rated at least 6 Amps.

And if you were to install new wires, using a reference table, you would have to use a minimum of 20 gauge wires, maybe a little bigger, like an 18 gauge.  Yes, the smaller the number, the bigger the wire.  In aviation they like aluminum (lighter, but current carrying ability is less than copper).

Rules of thumb:

• The higher the resistance, the higher the voltage in front of it.
• R up = A down  (As resistance is increased, the flow decreases)

Simple DC Electrical Circuit

Circuits are defined by the way they are connected: in Series; in Parallel; or a combination of both.

In order to call something a circuit, it must have: a Power Source; a Device to be powered; and wires or conductorsto move the electricity from one point to the other.  In addition, that electricity must travel from the power source to the device, and back to that power source.  In other words, it must go in a a circle or complete a circuit.  Without those conditions, it cannot work.

In electrical terminology, we need 3 components:

1. Source (the Battery)
2. Path (the wires)
3. Load (light bulb)

This circuit is complete, but the battery will discharge completely for the light to go off.

So, to make this circuit practical, we need to add a Control or a Switch, to turn it ONor OFF at will.  A two position switch will be either ON (closed circuit) or OFF (opencircuit).

In the drawing to the left, the Switch is turned OFF, of in the Open position.  Electricity from a battery cannot travel through the air, and the circuit is turned OFF.

Can electricity travel through the air? Yes, it can depending on it’s characteristics.  Not too much of a distance (very small gap between two conductors).  Or a very high voltage.  Voltage can be defined as the pressure existing in a circuit.  Compared to the pressure of water in a hose: if you have the very high water pressure from a nozzle, you can watersomething 20 yards away.  The same goes for electricity.

The Voltage or Pressure from a motorcycle battery is around 12 Volts (not much pressure).  Compare to the voltage in a Spark Plug: 20,000 to 70,000 Volts, and yes, in a Spark Plug, electricity travels between the electrodes, for the purpose of igniting the fuel/air mixture in the combustion chamber of an engine.

In this drawing, the circuit is powered and the electricity is flowing through it.  The switch is turned ON or the circuit is Closed.  Electricity flows from the battery, through the wires, the switch, the bulb, then the wire, and it returns back, until the battery gets discharged.

In addition, on motorcycles, to get to the simplest circuit possible, there are two more modifications to be made to this circuit:

• A circuit protection component or Fuse
• Use of the Frame and Engine to conduct electricity.

In the next post, I will show the example of the Tail Light circuit on a Honda CB750.

Electricity Lessons Order of Study

Electrical Power Sources on a Motorcycle

Very simply said, there are two Power sources on your motorcycle:

Stored electricity in your battery (DC or Direct Current)

You can define a few different types of Batteries:

1. The oldest is the conventional battery or Wet Cell.  Easily recognizable by it’s vent tube (on motorcycles), vented caps on cars (no longer in use for cars).  This battery must be maintained on a regular basis, by topping off the electrolyte with distilled water.  The voltage or potential difference for a fully charged conventional battery should be between 12.4V and 12.8V.  To measure the voltage of a battery, simply set a multimeter in Volts DV and put the black probe on the negative, and the red probe on the positive of the battery.
2. Then came the Maintenance Free battery whose voltage should be fully charged 12.6-13.2V. By it’s name this battery is somewhat Maintenance Free.  I say somewhat because part of maintaining a battery consists of keeping the posts clean (no corrosion or sulfate); and recharging is what not in use.  But NEVER add any liquid to it.. Matter of fact, if the battery has been correctly prepared by your seller, it shouldn’t have any liquid.
3. Then Harley Davidson & GM created the Absorbed Glass Mat battery.  Also a maintenance free battery, with the added plus, that it can be shipped without any type of warning labels, because it doesn’t have any spill-able corrosive agent.  The voltage for a fully charged one is 12.9-13.2V.
4. And the latest (as of 2010) is the Gel battery, a combo of MF & AGM.  No liquid.  Voltage fully charged: 12.8-13.2V(same as an AGM).




Generated electricity, produced by an Alternator type device, creating Alternating Current of AC

There are different types of those electricity generation devices:

1. One commonly called and Alternator.  This what you find on most cars, and only a few models of motorcycles.  This system cannot function without a charged Battery connected to it.  Just like the ones on cars, all the components are in one part called an Alternator.  You can find those on some older models Yamaha, a few more recent Kawasaki’s, a few large models Suzuki’s.  Used mostly on some touring models, and not on Sportbikes.
2. Then a similar one in concept but different in it’s construction.  Honda uses this type similar to an Alternator, but where the components are not all included in one device.  The true name of this concept is Electromagnetic System.
3. Finally, the most common system is the Permanent Magnet System. Which in turn has 3 different types defined by the number of coils used: 1/2 wave; Full wave (was a favorite for most Harley Davidson models, and still in use on most); and 3 phase. Suzuki has implemented on called Center Tap of a fourth phase.
Now, all of the ones described above have the purpose of keeping the battery in a good state of charge, while the engine is running.
• Then you have the various generation devices for the purpose of ignition or creating a spark in the combustion chamber.  I will address those at a later date.
Electricity Lessons Order of Study

The Puppet Masters

It points to The Payseur family (French roots), the head of the snake, the World's Puppet Masters.  They however may not be able to control the Rothschilds and Rockefeller.
Daniel Payseur (adoptive name, real name Crown Prince Louis), son of Marie Antoinette and King Louis XVI, is the beginning of this most powerful family in the World.
This family more powerful than The Rothschild or Rockefeller, calls the shots. They control the Federal Reserve and own Bank of America. Both of those entities, the FED and Bank of America, launder drug money for the CIA.
Their ancestors were the Ramses of Egypt and the Piso of Ancient Rome.