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

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 down the motorcycle ignition switch 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

Select a tab below to view 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.

 

Motorcycle Ignition Switches Simplified

6 wire motorcycle ignition switch

Most motorcycle ignition switches are connect & play devices. But they are not all the same. When sourcing a new motorcycle ignition switch, there are 3 essential things to find out first:

  1. The number of electrical contacts needed
  2. The type of contact(s) needed
  3. 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 key hole 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. Want to learn more? Don’t miss our ‘Guides’ tab above for a full breakdown.

 

Different Ignition Switch Specifications

Although the build and material quality of motorcycle ignition switches differs between manufacturers. In principle they are all the same. However, when sourcing upgrades and replacements, it’s important to consider evaluating the following before diving straight in.

2 wire motorcycle ignition switch

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 periods can reduce overall lifespan.

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

 


 

Mechanical dimensions

Getting the dimensions right when buying a new ignition switch 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.

 

Electrical connectors

motorcycle electrical connector

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

Top Tip

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

So, 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…

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

 

Ignition Switch Diagrams and Schematics

Click on a pane below to find links to our motorcycle ignition mechanical and electrical diagrams.

 

Ignition switch wiring diagrams

Huge buttons to navigate to Lamberts Bikes motorcycle ignition switch wiring diagrams. For simplicity, we’ve used the number of wires variable to categorize each ignition switch wiring diagram.

 

2 Wire Ignition Switch Wiring Diagram Links

2 wire ignition switch wiring diagram (SPST-NO)

 

3 Wire Ignition Switch Wiring Diagram Links

Isolated output 3 wire ignition switch wiring diagram (SPDT-NO)

Combined output 3 wire ignition switch wiring diagram (SPDT-NO)

 

4 Wire Ignition Switch Wiring Diagram Links

4 wire ignition switch wiring diagram (DPST-NO+NC)

 

5 Wire Ignition Switch Wiring Diagram Links

5 wire ignition switch wiring diagram (DPST-NC+2xNO)

 

6 Wire Ignition Switch Wiring Diagram Links

6 wire ignition switch wiring diagram (3PST-NC+2xNO)

 

Ignition switch mechanical drawings

No available content is known to us yet in this category.

Ignition 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.

4 wire motorcycle ignition switch

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)

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 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 another.

 

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, this standard has been adopted industry wide. Today, almost every electrical contact on a motorcycle has been standardised with a numerical code. More on this in a future development.

 

Motorcycle Ignition Switch Testing

Testing a motorcycle ignition switch is straight forward, 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 multi-meter can provide loads of useful insights.

Let’s look at how to gather and analyse basic resistance measurements.

ohm symbol

 

Closed and open electrical contacts

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.

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.

Here’s our quick step by step guide for testing a motorcycle ignition switch.

 

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. What insights have been gained regarding the condition of the electrical contacts?

 

Analysing the 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 (>1,000,000ohms). 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

5 wire motorcycle ignition switch

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 multi-meter. 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 Test Results

Fluctuations in resistance across an electrical contact are not a good thing. Resistance measurements should only change during required transitions. Where the results should show 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

3 wire motorcycle ignition switch

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 bikes

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 may require an ignition switch with a higher current capacity rating.

 

Negative and positive earth wiring

Electrical contacts have no preference which way current flows. Therefore, ignition switches are compatible with both negative and positive earth motorcycle wiring (unless otherwise stated by the manufacturer).

 




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