A constantly on neutral light is a pain in the ass. I understand exactly what it’s like. Sooo frustrating, but not to worry, this post will have you in the right gear.
The top 2 reasons an ATV or Motorbike neutral light stays on include:
- Ground wire fault
- Faulty or sticking neutral switch
By the end of this short post, you’ll understand why your neutral warning light stays on, how to diagnose it and how to fix it.
What’s the Neutral Switch For?
A neutral warning light was designed initially to help the rider find neutral when pulling to a stop. Today, some bikes use the neutral switch as part of the safety starting system. The bike must be in neutral with the light illuminated before the engine was permitted to crank or start.
It’s a simple and effective way to prevent unintended in gear starts. Not all bikes use the neutral switch in the same way. Your bike could instead use a safety switch fitted to the clutch lever to prevent unintended in-gear starts or indeed some ATVs employ the brake switch as part of the safety lock-out system. It really is model and year-specific.
Whichever safety system your bike has, the neutral switches themselves all work pretty similarly.
How Does Neutral Switch Work?
The neutral safety switch is a simple on-off switch that’s fitted to the transmission. The most common type is the electro/mechanical ball switch.
The shift lever acts on the ball sensor and completes a ground path to the transmission casing through the body of the switch itself, but only when neutral is selected.
The components of the system include:
- Power supply to dash neutral warning light
- Dash mounted warning light with replaceable bulb
- Ground supply to dash mounted warning light
- Transmission mounted neutral switch providing a ground path for the neutral dash warning light (and provides a signal to ECU or CDI if lock-out equipend)
Ground Wire Fault
The most common cause of a neutral light staying on is a short to ground. A short to ground is where the wiring simply rubs off an engine or chassis component, providing a shorter path for ground.
The result is the dash light illuminates and stays on, no matter what gear you’re in.
How to diagnose a neutral wiring or switch fault?
If you have done any work recently on the bike, check that area first.
- Your neutral switch will be mounted at the transmission, google your make and model to pinpoint it.
- Remove the wire from the switch and check dash bulb.
Two outcomes are likely:
1 – The neutral light goes out, go ahead and replace the neutral switch, it’s most likely faulty.
2 – The light stays on even though the switch is disconnected. You have a short to ground, somewhere between the switch and the dash panel. (see below)
How to find a neutral wiring short to ground?
A short as you know means the wiring is making a shorter path to the ground. The chassis of your bike is the ground side of the circuit and so the wiring needs only rub off the chassis to turn on the light.
Follow the single wire from the switch (or it may be detached and grounding) backward to the dash-mounted light. Somewhere along the way, the wiring has rubbed off the chassis or possibly another ground wire.
It’s not uncommon to pinch the ground wire when working on other components. Pinching the wire will cause it to ground.
As the switches are mechanical, they wear out, and before they stop working altogether, they usually make a nuisance of themselves by sticking in the on position. Depending on how your switch works, removing them and freeing them with a little tap of a plastic screwdriver handle may solve the issue short term, but the permanent solution is a replacement.
Replacing the neutral switch
Replacing the neutral switch is easy and requires just a few tools and obviously a new neutral switch. It is possible for an ATV to have a neutral, high, low, and reverse switch. Be sure you are working on the correct switch.
If in any doubt, disconnecting the switch terminal will kill the dash light, and grounding it on the chassis will illuminate it. Dirt bikes will only have a neutral switch fitted.
The process is as follows:
- Place bike in neutral
- Locate the switch
- Remove the wiring harness block connector
- Remove the switch fasteners, or could be a threaded body type switch
- If the switch the switch
- When fitting a new switch, be careful to replace the seal and don’t over tighten
Or if your ride is an ATV you’ll find parts here on the ATV parts page.
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