Do you have a motorcycle, ATV, moped or other vehicle with a 5 pin CDI ignition system that’s having issues starting or running? Troubleshooting and fixing ignition problems can be frustrating and seem overwhelming for someone without much mechanical experience.
The good news is that by learning how CDI systems work and using the correct 5 pin CDI wiring diagram for your particular model, you can diagnose and fix ignition issues on your own and get your wheels back on the road.
In this complete guide, you’ll learn:
- How 5 pin CDI ignition systems work
- The purpose of each wire in a CDI wiring harness
- How to read a basic 5 pin CDI wiring diagram
- How to troubleshoot no spark problems
- Stator, rectifier, pickup coil and other CDI component wiring
- Tips for testing CDI system parts to identify failures
And much more! Let’s get started.
Table of Contents
How Does a 5 Pin CDI Ignition System Work?
CDI stands for Capacitor Discharge Ignition. Unlike old points and condenser ignition systems, CDI uses electronic switching components to generate the high voltage for the spark plug instead of mechanical contact points.
The main parts of a CDI system are:
- Stator – The stator is essentially a generator made up of wire coils around iron cores. As the magnets on the flywheel pass by the stator, it generates an AC voltage which is sent to both the CDI box and the rectifier. The stator is the power source for the entire ignition system.
- Rectifier – The rectifier converts the AC voltage from the stator into DC voltage to charge the battery and power other electrical components.
- CDI Box – This is the “brain” of the system. When it receives a pulsing signal from the pickup coil, it discharges the stored energy in its capacitors to create a high voltage spark. This voltage travels through the ignition coil and jumps the spark plug gap to ignite the air/fuel mixture in the cylinder.
- Pickup Coil – As the flywheel magnet passes the pickup coil, it generates a small AC voltage. This signal tells the CDI box when to fire the spark plug.
- Ignition Coil – Steps up the voltage from the CDI box to the very high levels needed to jump the spark plug gap and ignite the mixture.
Now let’s look at the specifics of the 5 pin CDI wiring harness and diagrams.
5 Pin CDI Wiring Diagram Overview
On a 5 pin CDI system, you will find 5 different colored wires coming out of the CDI unit:
- Green – Connects to pickup coil signal input
- White – Connects to AC input from stator
- Red – Main power source (+12V from battery)
- Black – Main ground (- connection to battery)
- Blue – Output to ignition coil
The green wire brings the pulsing signal from the pickup coil to the CDI box so it knows when to fire the spark plug.
The white wire connects the CDI box to the AC voltage output wires from the stator. This provides power to the CDI system.
The red wire goes to the positive + terminal of the battery and serves as the main power feed for the CDI box.
The black wire provides the ground connection back to the negative – terminal of the battery.
Finally, the blue wire sends the high voltage from the CDI unit to the primary coil on the ignition coil. This voltage is stepped up by the ignition coil and sent to the spark plug.
That covers the basics of what each wire in a 5 pin CDI harness does. Next let’s look at some more detailed wiring diagrams.
Stator Wiring Diagram
The stator is a key component that must be wired properly for the CDI system to work. Here is a stator wiring diagram:
- The yellow wires go to the rectifier to be converted to DC charging voltage for the battery. There are usually two yellow wires.
- The white wires connect to the CDI box AC input. There should also be two white wires.
- Some stators also have an additional green wire that connects to the CDI box signal input along with the pickup coil green wire.
When testing a stator, you want to make sure it is putting out the specified AC voltage on the white and yellow wires. If the stator is bad and not producing adequate AC voltage, the CDI system will not have power to generate a spark.
Rectifier Wiring
Here is how the rectifier is wired:
- Yellow wires – Come from stator AC output and input to rectifier
- Red wire – Goes to positive terminal of battery
- Black wire – Goes to negative terminal of battery
The rectifier converts the AC from the stator into DC to charge the battery. Make sure these connections are good and that the rectifier is mounted to a metal surface on the frame or engine for proper heat dissipation.
If the rectifier is worn out, it may need to be replaced. Use a multimeter to check for adequate charging voltage coming out of the rectifier to the battery.
Pickup Coil Wiring
The pickup coil generates the signal that tells the CDI box when to fire the spark plug.
Here is how it is wired:
- Green wire – Goes to CDI box signal input
- Black wire – Grounds pickup coil
When testing a pickup coil, you want to check the resistance and ensure it puts out a pulsing AC voltage within the proper range when the flywheel magnet passes by. If not, the pickup coil should be replaced.
Ignition Coil Wiring
Here is how the ignition coil is wired into the system:
- Blue wire – Comes from CDI box output
- Red wire – Goes to positive battery voltage
- Black wire – Grounds ignition coil
- High tension lead – Goes to center of spark plug cap
The ignition coil steps up the CDI box voltage to the high levels needed to jump the spark plug gap and ignite the mixture. Make sure all coil wiring is in good shape and that the primary and secondary resistance values are to spec.
Troubleshooting No Spark Issues
Now that you understand how a 5 pin CDI system works and how each component is wired, let’s go over some tips for troubleshooting no spark problems.
Here are the steps:
- Inspect all wiring – Visually inspect every inch of wiring from the CDI box to the battery, stator, pickup coil, ignition coil etc. Look for any loose, disconnected, shorted or cut wires that could interrupt power flow through the system.
- Check main fuses – Make sure the main fuse for the CDI system is not blown. Also check the ignition coil fuse if there is a separate one.
- Test battery – Check that the battery is charged and putting out 12+ volts. The CDI system will not function properly with low voltage.
- Verify CDI ground – Make sure there is a solid ground connection from the CDI black wire to the negative – battery terminal.
- Check stator – With the engine running, use a multimeter to verify the stator is putting out the specified AC voltage on its white output wires that connect to the CDI box. If not, the stator will need to be replaced.
- Test pickup coil – Check the resistance of the pickup coil with a multimeter. You can also backprobe the pickup coil green wire while cranking the engine to see if it is generating a pulsing voltage signal. If not, replace it.
- Check CDI input – Make sure the green and white input wires to the CDI box are getting the proper pulsing and AC voltage signals. If they are, then focus on the CDI output side.
- Verify ignition coil – First check all coil wiring. Then use a multimeter to check the primary and secondary resistance values per your repair manual specs. Replace the coil if out of spec.
Methodically testing each component in the CDI ignition system using the 5 pin CDI wiring diagrams in this guide will allow you to zero in on the failed part preventing spark.
With the right troubleshooting approach and some basic mechanical skills, you can save money by fixing your own no spark problems. Let us know in the comments if you need any other help!
Conclusion
Understanding how 5 pin CDI ignition systems operate and reading wiring diagrams are the keys to successfully troubleshooting and fixing no spark issues.
Use this guide to learn how stators, rectifiers, pickup coils, CDI boxes and ignition coils function and connect together in the overall system.
Checking each part and verifying AC and DC voltages and resistance values will lead you to the faulty component.
With this complete 5 pin CDI wiring diagram troubleshooting reference, you’ll have the knowledge to get your motor running smoothly again!
