Where Is The Third Pole On A Chainsaw Coil: Wiring Guide

On tri-leg modules, the third pole is the narrow center leg facing the flywheel magnets.

If you have ever asked where is the third pole on a chainsaw coil, you are not alone. I’ve set up, repaired, and tested hundreds of ignition modules in pro shops and home garages. In this guide, I will show you exactly where is the third pole on a chainsaw coil, why it exists, how to spot it on different brands, and how to set it up the right way. You will get clear steps, photos-in-mind detail, and simple checks you can do today.

Understanding the chainsaw ignition coil

A chainsaw coil, also called the ignition module or magneto, makes spark from the flywheel magnets. The flywheel spins past the coil’s metal legs and induces voltage. That voltage fires the plug at the right time.

Most modules sit next to the flywheel with two visible metal legs. Some digital coils add a narrow center leg. This is what many users call the third pole. It helps shape timing and spark at high rpm.

Where is the third pole on a chainsaw coil? Explained

Here is the short, clear map for where is the third pole on a chainsaw coil:

• On three-leg modules, the third pole is the slim center leg between the two wide legs.
• It faces the flywheel and shares the same air gap as the outer legs.
• It does not get a separate gap or wire. It is part of the laminated core.

On many saws, folks also use where is the third pole on a chainsaw coil to ask about the small spade terminal. That spade is not a pole. It is the kill switch terminal. The coil’s body gets ground through its bolts. The spark plug gets high-voltage from the thick lead.

Real-world note: On some Stihl and Echo digital modules, that center leg is easy to see. On many Husqvarna and Poulan models, you will only see two legs. If you wonder where is the third pole on a chainsaw coil on those saws, the answer is simple: there is no third leg at all.

How to identify the third pole on your saw

If you are still unsure where is the third pole on a chainsaw coil, use this simple check.

• Remove the top cover and the starter housing.
• Look at the ignition module beside the flywheel.
• Count the iron legs that face the flywheel magnets.
• If you see two wide legs and a thin center leg, that thin center leg is the third pole.
• If you only see two legs, your coil does not have a third pole.
• Find the small spade connector. That is the kill switch wire, not a third pole.

Tip from the bench: Wipe dust away with a dry brush. Oil can hide the center leg. If you wonder again where is the third pole on a chainsaw coil, shine a small light across the laminations. The center leg will cast a thin shadow line between the two outer legs.

Setting the air gap and orientation

You found where is the third pole on a chainsaw coil. Now set it right. The air gap sets spark strength and timing.

• Spin the flywheel so the magnets align with the coil legs.
• Slip a non-magnetic shim between the legs and the flywheel. A business card works in a pinch.
• Most saws use 0.20–0.40 mm (0.008–0.016 in). Check your service spec.
• Loosen the coil bolts. Let the magnets pull the legs to the shim. Tighten the bolts.
• Remove the shim and spin the flywheel to confirm no rub.

Important detail: You do not set a separate gap on the center leg. The gap is even across the two outer legs, and the center leg follows. If you ask where is the third pole on a chainsaw coil to adjust it, remember it is part of the same face. Treat all legs as one plane.

Brand patterns and variations you will see

Different brands take different paths. This is why many people ask where is the third pole on a chainsaw coil.

• Stihl and Echo. Many modern digital modules have a slim center leg. That is the third pole.
• Husqvarna and Jonsered. Many models use two-leg modules. No third leg is present.
• Poulan and Craftsman. Budget models often have two legs. Combo stator plates for lights or charge coils may show extra poles, but those are not the ignition module’s third pole.
• Aftermarket coils. Shapes vary. If you ask where is the third pole on a chainsaw coil on an aftermarket part, compare it to the OEM photo in the parts list.

I always check the parts diagram first. If the drawing shows a three-leg face, that answers where is the third pole on a chainsaw coil for that model at a glance.

Testing and troubleshooting the coil

Sometimes the real question behind where is the third pole on a chainsaw coil is about no-spark issues. Use these quick tests.

• Kill switch test. Pull the small spade wire off the coil. Try for spark. If it sparks now, the switch or wire is shorted.
• Resistance check. Primary and secondary readings vary by brand. Use the spec from a service manual. Readings far off spec suggest a bad coil.
• Spark tester. Use an inline tester. You should see a strong blue flash under pull.

Common faults I see in the shop:

• Bent legs from prying during removal.
• Gap set too wide. Weak spark at hot restart.
• Kill wire pinched under the shroud. Constant ground, no spark.

If you checked where is the third pole on a chainsaw coil and set the gap right, but still have no spark, swap in a known-good plug. Many “bad coils” are bad plugs.

Safety tips, setup mistakes, and pro tricks

Even a simple task can go wrong fast. Here are the things I teach new techs who ask where is the third pole on a chainsaw coil.

• Disconnect the spark plug before you work near the flywheel.
• Use non-magnetic shims. Steel shims can skew the gap or stick to magnets.
• Do not grind or file the coil legs. Keep the faces flat and clean.
• Route the kill wire away from the flywheel. Rubbing will strip it and short the spark.
• If you install an aftermarket part, dry-fit the module. Confirm the legs sit square to the flywheel face.

Pro tip: When you confirm where is the third pole on a chainsaw coil, snap a quick photo with your phone. That way you can match the angle and stand-off when you reassemble later.

Frequently Asked Questions of where is the third pole on a chainsaw coil

Is the third pole the same as the kill switch terminal?

No. The third pole is a small center leg on some coils. The kill switch terminal is a separate spade connector used to ground out spark.

Do all chainsaws have a third pole on the coil?

No. Many coils only have two legs. If you wonder where is the third pole on a chainsaw coil on those saws, it does not exist.

How do I set the gap on a three-leg coil?

Set the gap across the face using a single shim. The center leg follows the same plane, so you do not gap it on its own.

Will a wrong gap damage the coil or flywheel?

A very tight gap can rub and score the faces. A very wide gap can cause weak spark and hard starts, but it rarely breaks parts.

Can I test the coil without a multimeter?

Yes. Use an inline spark tester and a known-good plug. If you have spark with the kill wire removed, the coil is likely fine.

Conclusion

If you started out asking where is the third pole on a chainsaw coil, you now know how to spot it, how it works, and when it is not there at all. The third pole is the slender center leg on some digital modules, not the kill switch spade, and it shares the same air gap as the outer legs. With a clean view, a simple shim, and a few quick tests, you can set timing, restore spark, and get back to cutting.

Put this guide to work on your saw today. If it helped, subscribe for more small-engine tips or drop your questions in the comments.