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Motorcycle Ignition Switch

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Motorcycle Ignition Switch Introduction

This is the ultimate guide to the worthy motorcycle ignition switch.

We’ve included a whole host of learning material and educational data, to help get to grips with these vital security devices.

Thinking of sourcing a new ignition switch?

Start with the basics. Skip out the waffle.

Find out all that you need to know before making your next purchase.

6 wire motorcycle ignition switch
A 6 wire motorcycle ignition switch.

Kill and lock off electric circuits with the twist of a key…

Explanations everyone can understand. Layered into what you need to know. Before building on complexity until you’ve had enough and beyond.

We’ve even stripped the motorcycle ignition switch down to its basic engineering principles.

Wrapping up each principle into an everyday system that does exactly what an ignition switch needs to do…

“Kill and lock off electric circuits with the twist of a key.”

Motorcycle Ignition Switch Technical Data

Browse below to find detailed, technical data about motorcycle ignition switches. If you think we’re missing something get in touch and we can publish it here for everyone to see.


The Basics

What is a Motorcycle Ignition Switch?

A motorcycle ignition switch is no different to any other mechanical electrical switch…

Using the kinetic energy of a hand movement, electrical contacts are opened or closed. Allowing or stopping the flow of electrical energy.

2 wire motorcycle ignition switch
A photograph of a 2 wire motorcycle ignition switch


Ignition Switches Devices Simplified

Most motorcycle ignition switches are plug & play devices. But they are not all the same.

When sourcing a new relay there are three essential things to find out first:

  • The number and type of electrical contacts needed.
  • The type of electrical contact(s) needed.
  • The mechanical fitment.

Type of Ignition Switch Contacts

An electrical switch is either normally open or normally closed.

‘Normal’ refers to the electrical contact position in its rest state. For motorcycle ignition switches the normal (or rest) state is with the key in the off position.

  • Normally open contacts are useful for switching electrical supplies. Such as main power rails, lights and brake switches.
  • Normally closed contacts are commonly used for kill switches and alarm activation signals.

Consider the application wisely. Ignition switches with more than one electrical contact are available for more complex modifications.


Electrical contacts in drawings

Here is the standardised method of illustrating electrical contacts in a wiring diagram (these are the actual templates used in all of Lamberts Bikes motorcycle part wiring diagrams).

normally open switch contact
A normally open switch contact (NO)
normally closed switch contact
A normally closed switch contact (NC)

The illustrated vertical centre lines join up contacts that operate with the same action. On one end of this centre line should be a small illustration to show the action that operates the contacts.

For a motorcycle ignition switch a keyhole illustration would be shown. For other applications the action illustration may show a push button or pull switch.


Multiple Contact Ignition Switches

There is a huge range of motorcycle ignition switches available on the market. Many of which have more than one electrical contact.

Engineers use simple abbreviations to describe the type, orientation and number of electrical contacts in a switch or relay.

A basic knowledge of this abbreviated coding system will prove useful when sourcing replacements and upgrades.

Specifications

Although the principle operation of motorcycle ignition switches are the same, there are many different specifications, formats and designs.

As always, the overall build quality of ignition switches varies between manufacturers.

Therefore, when sourcing a new relay, it’s important to consider evaluating the following before diving straight in:

  1. Number and type of output contacts
  2. Output contact(s) current capacity
  3. Mechanical dimensions
  4. Connectors
  5. Negative and positive earth wiring

Continue to read the sections below to gain a more detailed understanding…



Number and type of output contacts

When sourcing replacements, we recommend a quick review of any wiring diagrams for the model of motorcycle. This a guaranteed method to identify the number and type(s) of electrical contacts the original motorcycle ignition switch had.

Motorcycle ignition with more than one electrical contact and contact orientation are widely available. However, even a simple 2 wire ignition switch can have a normally open or a normally closed contact.

With all this complexity, sourcing to specific requirements can be tough. Be flexible and consider all options. Having a spare contact or two could prove to be a wise idea.


Output contact(s) current capacity

The required current capacity of the outputs will be application dependant. Our words of wisdom would be to go bigger.

Running electrical contacts close to their capacity for extended period can reduce their overall lifespan.

For pulsing applications, check the on and off durations in the specifications. This will give an insight into how the design will function in the real world.

Always check the max current specifications against a calculated electrical load. Instantaneous current specifications are also useful for heavy load circuit designs.


Mechanical Dimensions

3 wire motorcycle ignition switch
A photograph of a 3 wire motorcycle ignition switch

Getting the dimensions right when buying a new relay will save you whole lot of headache when it comes to installation.

Consider these two things:

  1. The space that’s available
  2. The bolt hole dimensions
    • The gap between each bolt hole (if there’s more than one)
    • The diameter of each bolt hole

It’s also wise to check the length of cable that’s available on your loom. Just to make sure that it will reach.


Connectors

Unless you plan on crafting your own electrical connections this can make sourcing a replacement rather problematic.

Connector Care Top Tips

Most motorcycle connectors have replaceable terminal pins. This means that the pins can be relocated in the connector housing.

Consequently, there’s no need to worry don’t worry about wire positioning in connectors. This can be remedied easily with a sewing needle at home…

  1. Lightly bend down the latch on the terminal pin to remove it from its connector housing.
  2. Then, make sure that the latch is still in good condition, before finally clicking it into the location you need.

Negative & Positive Earth Wiring

For most motorcycles this section can be overlooked.

The bulk of motorcycles on the market are negative earth.

And motorcycle stator manufacturers have accommodated this trend nicely.

Positive Earth Wiring

For those classic renovators among us that love positive earth set ups…

You can use any ignition switch that meets your needs.

Ignition switches are merely an electrical contact, therefore electricity can flow in either direction. This is due to the fact that electrical contacts have no preference to which way current flows.

So positive, or negative earth, an ignition switch will work (unless otherwise stated by the manufacturer).


Guides to Ignition Switches

Ignition switches are very simple devices to wire and connect up. Follow these simple guides to get clarity before you start…


Electrical Switch Contact Abbreviations

Have you ever noticed abbreviations being used describe the contact configuration for an electrical switch? Such as SPST, DPDT or even 4PST?

Engineers use simple abbreviations to describe the type, orientation and number of electrical contacts in a switch or relay.

A basic knowledge of this contact abbreviating system will prove useful when sourcing replacement and upgrade motorcycle ignition switches.

Abbreviation basics

We’ll use the example SPST-NO:

  • The first two letters define the pole count (SPST-NO)
  • The next two letters define the throw count (SPST-NO)
  • Finally, the last two letters define the open/closed state of the switch in its normal/rest position. (SPST-NO)
4 wire motorcycle ignition switch
A photograph of a 4 wire motorcycle ignition switch

So, SPST-NO translates to Single Pole, Single Throw – Normally Open.

It’s also worth noting that numbers are frequently used to the define the pole count. The numerical representation of SPST-NO is 1PST-NO.

Let’s take a look at what’s behind this pole, throw and state jargon…


Pole Counts

The pole count of a motorcycle ignition switch defines the number separate electrical circuits it operates. Each circuit has its own electrical contacts and connection terminals. Electrical insulating materials are used in the switch design the isolate the circuits from each other.


Throw Count

The throw count of a motorcycle ignition switch defines the number of output terminals a pole’s common terminal can connect to. Throw count is an important consideration for applications where additional key positions are required (i.e. park, lights, alarm).


NO and NC codes

This has been briefly covered in ‘The Basics’ tab above. An electrical switch is always either normally open or normally closed. NO and NC are respective abbreviations.


DIN Terminal Codes

The German Institute for Standardisation (DIN) created the standard DIN 72552 for the labelling of automotive electrical terminals.

Over time, the DIN standard has been adopted industry wide. Today, almost every electrical contact on a motorcycle has been standardised with a numerical code.

To learn more on the DIN standard, explore our post on motorcycle relay wiring.


Motorcycle Ignition Switch Testing

Testing an ignition switch is often straightforward, providing that you know what you’re looking for. Apart from the obvious signs of visual damage or smell of electrical failure.

Some simple tests with an everyday multimeter can provide loads of useful insights. Let’s look at how to gather and analyse basic resistance measurements.


Testing Open Electrical Contacts

normally open switch contact
A normally open switch contact (NO)

Open contacts need to create a path of high resistance to properly turn off the electrical circuit.

Faulty open contacts allow electrical current to pass through. This can lead to the unwanted electrical activity and even drain the motorcycle battery.

Therefore, when measuring across a closed contact, expect a high resistance.


Testing Closed Electrical Contacts

normally closed switch contact
A normally closed switch contact (NC)

Closed contacts need to provide a path of low resistance for the electrical circuit to be efficient.

Increased resistance across a closed contact generates heat which reduces system efficiency and increases wear and tear.

Therefore, when measuring across a closed contact, expect a really a low resistance.



Step by step ignition switch contact test

  1. Disconnect the ignition switch from the motorcycle wiring loom.
  2. Rotate the key to the switches off position.
  3. Test and make note of the resistance across all contacts.
    • For closed contacts we’re expecting to measure low resistance values.
    • For open contacts we’re expecting to measure high resistance values.
  4. Rotate the key and repeat step 3. Continue to repeat step 3 for every key switch position.
  5. Review the measurements taken.
  6. What insights have been gained regarding the condition of the electrical contacts?
    • Read on to further understand your results…

Analysing Ignition Switch Contact Test Results

For closed contacts, resistance values measuring greater than roughly 1 ohm show that the contact is starting to suffer wear and tear. Consider replacing the ignition switch.

For open contacts, measured resistance values should be in the megaohm range (>1,000,000 ohms). Lower readings show that the contact has failed or is starting to suffer wear and tear. Consider replacing the ignition switch.

The huge difference in the resistance values of normally open and normally closed switches make it quick and easy to identify contact failures.


Mechanical Transition Testing

Another common ignition switch failure is contact bouncing. Usually caused by the natural vibration of the bike.

Potential contact wear and the mechanical function of the switch assembly can be tested with an everyday digital multimeter. Here’s how:


Step by step ignition switch transition testing

  1. Disconnect the ignition switch from the motorcycle wiring loom.
  2. Rotate the key to the switches off position.
  3. Test and make note of the resistance across one of the electrical contacts.
  4. Slowly rotate the key from one position to the next and back again
    • Make note of how the resistance changes between each transition.
      • We’re looking for a dramatic, quick and yet smooth change in resistance.
  5. Move your test probes to a different electrical contact and repeat from step 3. Continue to repeat from step 3 for each electrical contact.
  6. Review the measurements taken.
    • What insights have been gained regarding the mechanical condition of the ignition switch?

Analysing the Transition Test Results

Fluctuations in resistance across an electrical contact are not a good thing.

Resistance measurements should only change during required transitions.

Results should show a dramatic, quick and yet smooth changes in resistance. If not, replace the ignition switch.

If any contacts fail to transition smoothly or when intended, replace the ignition switch.

The expected dramatic change in resistance as the switch transitions, should make it quick and easy to identify contact wear and failures.


Ignition Switch Compatibility

Here are a few things to extra points to consider regarding the cross compatibility of motorcycle ignition switches.



Electrical load

Running a motorcycle ignition switch close its maximum current capacity rating, for extended periods, will reduce its overall lifespan.

If possible, source an ignition switch with a little extra current capacity.


Voltage

With most replacement ignition switches, maximum voltage ratings are way above the system voltage of the motorcycle. However, ignition circuits generate much higher voltages on a bike than its power rail system voltage.

Maximum voltage specifications must be carefully reviewed when switching outputs from a motorcycle stator.


Modern motorcycles

It’s important to note the big electrical loads on a bike before souring a replacement ignition switch.

With fuel injection systems, ABS controls and ECU’s, your ride may require an ignition switch with a higher current capacity rating.


FREE Ignition Switch Wiring Diagrams

Huge buttons to navigate to Lamberts Bikes motorcycle ignition switch wiring diagrams. Download them direct to your device or view them online!



Ignition Switch Wiring Diagram Links

2 Wire Ignition Switch Wiring Diagram (SPST-NO)


Isolated 3 Wire Ignition Switch Wiring Diagram (SPDT-NO)


Combined Output 3 Wire Ignition Switch Wiring Diagram (SPDT-NO)


4 Wire Ignition Switch Wiring Diagram (DPST-NO+NC)


5 Wire Ignition Switch Wiring Diagram (DPSTDT-NC+2xNO)


6 Wire Ignition Switch Wiring Diagram (3PST-NC+2xNC)



Learn more…

To learn even more about your motorbikes power circuit, view “how do regulator rectifiers work?

Don’t miss our motorcycle parts knowledge database!



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